a jar contains 10 blue marbles and 11 red marbles. two marbles are drawn without replacement. what is the probability of getting two red marbles?

Answers

Answer 1

0.2620 is the probability of getting two red marbles.

What is probability?

Probability is a mathematical discipline that concerns with numerical figures of how probable an occurrence is to occur or how probably a statement is to be true. A number between 0 and 1 is the probability of an occurrence, where, broadly speaking, 0 denotes the event's impossibility and 1 denotes its certainty.

a jar contains 10 blue marbles and 11 red marbles.

So, there total 21 marbles are present.

Now among 21 marbles, 11 are red marble. So, odds of a red on the first are 11/21

Next, there are 20 marbles are present and 10 are red. So odds of a red on the second is 10/20.

For, probability both are red, just multiply

= (11/21) x (10/20)

= 0.2620.

To know more about probability refer to:

brainly.com/question/24756209

#SPJ4


Related Questions

Danny opened a savings account and deposited $100.00. The account earns 2% interest,
compounded annually. If he wants to use the money to buy a new bicycle in 3 years, how
much will he be able to spend on the bike?
nt
P(1 + 1)^²₁. where A is the balance (final amount), P is the principal
Use the formula A = P 1 +
(starting amount), r is the interest rate expressed as a decimal, n is the number of times per
year that the interest is compounded, and t is the time in years.
Round your answer to the nearest cent.

Answers

Answer: f = p * (1 + r) ^ n

f is the future value.

p is the present value.

r is the interest rate per time period.

n is the number of time periods.

time periods are months.

rate is the percent divided by 100.

p = 100

r = 6% per year / 12 = .5% per month / 100 = .005 per month.

n = 2 years * 12 = 24 months.

formula becomes f = 100 * (1 + .005) ^ 24

solve for f to get:

f = 112.7159776 = 112.72

that's how much Danny will be able to spend on the bike in 2 years.

Step-by-step explanation:

for every 8chin ups Melanie can do Theresa can do 5. If Melanie did 48 chin ups, how many fewer did Theresa do

Answers

Answer: Theresa did 18 fewer chin-ups.

Step-by-step explanation:

Melanie 8,16,24,32,40,48

Theresa 5,10,15,20,25,30

48-30=18

power 121.three consecutive prime numbers, each less than $100$, have a sum that is a multiple of $5$. what is the greatest possible sum?

Answers

The three greatest consecutive prime numbers where the sum is a multiple of 5 are 3, 5, and 7.

We have,

To find the three consecutive prime numbers with a sum that is a multiple of 5 and each less than 100, start by listing the prime numbers less than 100:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97

Check each combination:

(2, 3, 5): Sum = 2 + 3 + 5 = 10 (which is a multiple of 5)

(3, 5, 7): Sum = 3 + 5 + 7 = 15 (which is a multiple of 5)

(5, 7, 11): Sum = 5 + 7 + 11 = 23 (not a multiple of 5)

(7, 11, 13): Sum = 7 + 11 + 13 = 31 (not a multiple of 5)

(11, 13, 17): Sum = 11 + 13 + 17 = 41 (not a multiple of 5)

(13, 17, 19): Sum = 13 + 17 + 19 = 49 (which is not a multiple of 5)

(17, 19, 23): Sum = 17 + 19 + 23 = 59 (not a multiple of 5)

(19, 23, 29): Sum = 19 + 23 + 29 = 71 (not a multiple of 5)

(23, 29, 31): Sum = 23 + 29 + 31 = 83 (not a multiple of 5)

(29, 31, 37): Sum = 29 + 31 + 37 = 97 (not a multiple of 5)

(31, 37, 41): Sum = 31 + 37 + 41 = 109 (which is not a multiple of 5)

(37, 41, 43): Sum = 37 + 41 + 43 = 121 (which is not a multiple of 5)

(41, 43, 47): Sum = 41 + 43 + 47 = 131 (not a multiple of 5)

(43, 47, 53): Sum = 43 + 47 + 53 = 143 (which is not a multiple of 5)

(47, 53, 59): Sum = 47 + 53 + 59 = 159 (which is not a multiple of 5)

(53, 59, 61): Sum = 53 + 59 + 61 = 173 (not a multiple of 5)

(59, 61, 67): Sum = 59 + 61 + 67 = 187 (not a multiple of 5)

(61, 67, 71): Sum = 61 + 67 + 71 = 199 (not a multiple of 5)

(67, 71, 73): Sum = 67 + 71 + 73 = 211 (not a multiple of 5)

(71, 73, 79): Sum = 71 + 73 + 79 = 223 (not a multiple of 5)

(73, 79, 83): Sum = 73 + 79 + 83 = 235 (which is a multiple of 5)

(79, 83, 89): Sum = 79 + 83 + 89 = 251 (not a multiple of 5)

(83, 89, 97): Sum = 83 + 89 + 97 = 269 (not a multiple of 5)

Thus,

The three greatest consecutive prime numbers where the sum is a multiple of 5 are 3, 5, and 7.

Learn more about expressions here:

https://brainly.com/question/3118662

#SPJ12

Using the unit circle, on what interval is the cosine function increasing? (0, startfraction pi over 2 endfraction) (0, pi) (startfraction pi over 2 endfraction, startfraction 3 pi over 2 endfraction) (pi, 2 pi)

Answers

The interval where the cosine function is increasing is (π, 2π).

Finding the value of the cosine function in different intervals:

The cosine function for the interval (0, π/2) gives

cos(x) = cos(0) = 1

cos(x) = cos(π/2) = 0

So, the value of the function is decreasing in this interval.

Then, for the interval (0, π), it gives

cos(0) = 1; cos(π) = -1

So, the value of the cosine function is decreasing in this interval.

Then, for the interval (π/2, 3π/2), it gives

cos(π/2) = 0

cos(π) = -1

cos(3π/2) = 0

So, the value of the function decreases up to x = π and then increases up to the same value as before i.e., cos(π/2) = cos(3π/2).

Then, for the interval (π, 2π), the cosine function gives

cos(π) = -1

cos(2π) = 1

Thus, the cosine function in this interval increase from -1 to 1.

Therefore, in the interval (π, 2π), the cosine function is increasing.

This is explained by using a unit circle below:

Learn more about cosine function here:

https://brainly.com/question/17075439

#SPJ4

Answer:

D

Step-by-step explanation:

got it right

The average mass of 5 boys is 50 kilograms. Another boy’s mass is added and the average goes to 40 kilograms. What was the mass of the sixth boy?

Answers

The mass of the sixth boy is 80 kilograms.

What was the mass of the sixth boy?

It's important to note that a mean simply means the average of a set of numbers that are given. In this situation, the average mass of 5 boys is 50 kilograms. The total mass will be:

= 50 × 5

= 250 kilograms

In this case, when another boy’s mass is added and the average goes to 55 kilograms. The total mass will be:

= 55 × 6

= 330 kilograms.

The average mass of the last boy will be:

= 330 - 250

= 80 kilograms

Learn more about mean on:

brainly.com/question/1136789

#SPJ1

Complete questions

The average mass of 5 boys is 50 kilograms. Another boy’s mass is added and the average goes to 55 kilograms. What was the mass of the sixth boy?

Find the measure of angle f given the information below.


A= 122 degrees
E=48 degrees the image is below!!

Answers

Answer:

74

Step-by-step explanation:

if a is 122 b is 58

b is congruent to g to g=58

58+48=106

180-106=f

180-106=74

Jimmy, Johny, and Jolly worked part-time on the weekend to earn some extra money. Three of them together earned $57. If Johny earned twice as much as Jolly did and Jimmy earned $3 less than Johny did, how much did Jimmy earn?

Answers

On solving the provided linear equation question - Jolly = $17.4, Jimmy =2x-30  =4.8 and Johnny = 2x=34.8

What is a linear equation?

A linear equation has the algebraic form y=mx+b. where m is the slope and b is the y-intercept, consisting of a first-order (linear) term and a constant. If x and y are variables, the above is sometimes called a "two-variable linear equation".

Take Jolly's expenditure as x.

Jimmy would have spent twice as much as Jolly.

Johnny Equals 2x-30 if Johnny spent $30 less than Johnny.

Total amount spent: $57

Therefore,

[tex]x+ (2x-30) + 2x = 57\\ x+ 2x -30 +2x =57.\\ 5x = 57+ 30\\[/tex]

x = 87/5

x= 17.4

Now take is that - X= 17.4.

Jolly is that -  x= $17.4

Jimmy is that - =4.8

Johnny is that = =34.8

To know more about linear equation visit:
https://brainly.com/question/11897796

#SPJ1

Algebraic fractions which option is correct

Answers

Answer:

A

Step-by-step explanation:

because to solve this question the division would change into multiplication and the second fraction would be converted upside down

. if you start with 1/4, you can create an entire class of fractions equivalent to 1/4 like the one above, by multiplying 1/4 by different forms of what number?

Answers

If you start with 1/4, you can create an entire class of fractions equivalent to 1/4 by multiplying 1/4 by different forms of the number 1.

What are fractions?

The connection between two numbers, known as the numerator and the denominator, is expressed mathematically as fractions. The number of pieces is represented by the numerator, while the total number of components is represented by the denominator. For instance, if a pizza is cut into 8 slices and someone eats 3 of them, the fraction corresponding to the quantity consumed would be 3/8.

Diverse mathematical ideas, including division, ratios, and proportions, can be represented using fractions. They can also be used to represent decimal and percentage values, with the decimal point placed to the right of the numerator and the number of decimal places represented by the denominator.

To learn more about fractions, visit:

https://brainly.com/question/10354322

#SPJ4

Olivia want to have a 90 average in algebra, where tet count for 55%, quizze count for 30ge % and homework count for 15%. If he ha a 92 tet average and 100% HW average, what mut her quiz average be? Let x = the average of the

Answers

In order to score 90 average in algebra her quiz average should be  82%.

It involves calculating the result of multiplying a number of quantities by their sum, then dividing the result by the total number of quantities.

Given,

She has a test grade of 55%, a quiz grade of 30%, and a homework grade of 15%.

If she achieved a score of 92% on the test

Make x the number of tests,

x = (90 - (0.55(92) + 0.15(100)))/0.30

x = 82

To receive a 90 in math, Olivia needs to have a quiz average of 82.

One of the oldest subfields of mathematics, algebra covers number theory, geometry, and analysis. Algebra is also defined as the study of mathematical rules and symbols through the manipulation of those mathematical symbols.

Algebra covers a wide range of topics, from the study of abstractions to the solution of simple equations.

To learn more about  algebra

brainly.com/question/850007

#SPJ4

choose the best graph to match the given expression.
F(x)= [x+1]

Answers

Answer:

Step-by-step explanation:

I don't see a graph from which to choose.  Are the brackets in "[x+1]" supposed to be parentheses, or are they absolute value signs?

The graph of functions

(F(x) = (x+1), and

(F(x) = |x+1| are both attached.

The angles of a triangle are 44 degrees, 110 degrees, and 26 degrees. Classify the triangle

Answers

The measure of angles form an scalene triangle.

What is the angle sum property?

The angle sum property of a triangle states that the sum of the interior angles of a triangle is 180 degrees.

An angle requires two straight line, such that they're connected on one of their endpoints. The point of their joint is called vertex of that angle.

We are given that the angles of a triangle are 44 degrees, 110 degrees, and 26 degrees.

Since we know that angle sum property of a triangle;

44 + 110 + 26

180

Therefore, the measure of angles form an scalene triangle.

Learn more about the triangles;

https://brainly.com/question/2773823

#SPJ1

Find the slope (rate of change) of a line that passes through (-2, -3) and (1, 1).

1. 1/3
2. 1
3. 2
4. 4/3

Answers

Answer:

4. 4/3

Step-by-step explanation:

(-2, -3)   (1,1)

1+3/1+2=

4/3

The answer would be 4/3!

A large pizza at palanzio pizzeria cot $6. 80 plu $. 90 for each topping. The cot of a large pizza at guido' pizza i $7. 30 plu $. 65 for eachtopping. How many topping need ti be added ti a large pizza from palanziod pizzeria and guido' pizza in order for the pizza to cot the ane not including tax

Answers

2 toppings need to be added to a large cheese pizza from Palanzio's Pizzeria and Guido's Pizza in order for the pizzas to cost the same, not including tax.

Let x be the number of toppings to be added to each pizza and y be the total cost of pizza.

A large pizza at Palanxio's Pizzeria cot $6. 80 plu $. 90 for each topping.

So, we get an equation,

y = 6.80 + 0.90x

The cot of a large pizza at Guido's Pizza i $7. 30 plu $. 65 for eachtopping.

So, we get an equation,

y = 7.30 + 0.65x

 We need to find the number of toppings need to be added to a large cheese pizza from Palanzio's Pizzeria and Guido's Pizza in order for the pizzas to cost the same, not including tax.

Now let's equate the costs of both pizzas and solve for x.

6.80 + 0.90x = 7.30 + 0.65x

0.25x = 0.50

x = 2

Therefore, 2 toppings to be added to each pizza

Learn more about an equation here:

#SPJ4

three solutions of the equation y= -2x

Answers

Answer:

three solutions of the equation:

y = -2x - 1

=>

1) (0, -1)

2) (1, -3)

3) ( -1, 1)

Step-by-step explanation:

Write a rule for the n th term of the sequence. Then find a_{20}

$51,48,45,42,...$

Answers

The rule for the nth term of arithmetic sequence is a + (n - 1)d.

What is the nth term of arithmetic sequence?The difference between consecutive terms in an arithmetic sequence is always the same.An arithmetic sequence's nth term is given by a = a + (n - 1)d. The number d is known as the common difference because any two consecutive terms of an arithmetic sequence differ by d, and it can be found by subtracting any two terms a and an+1.

Here also,

We use the definition for the nth term of an arithmetic sequence:

an = a1 + (n - 1) d

Here first term (a1) = 51

common difference (d) = a2 - a1

                                      = 48 - 51

                                      = -3

We have to find 20th term,

a[20] = a1 + (20 - 1) d

         = 51 + 19 x -3

         = 51 - 57

         = - 6

Therefore 20th term of the sequence 51,48,45,42,... is -6.

To learn more about arithmetic sequence refer to :

https://brainly.com/question/6561461

#SPJ1

there are 5 children on your guest list and 40 people in total. what percentage of the people are children?

Answers

Answer: 12.5%

Step-by-step explanation:

5/40

0.125 x 100

12.5%

Answer:

2 children I believe so

Step-by-step explanation:

because you take 40%×5 and u will get 2

At a football stadium, 25% of the fans in attendance were teenagers. If there were 10 teenagers at the football stadium, what was the total number of people at the stadium?

Answers

Answer:

40 people

Step-by-step explanation:

25% = 10

50% = 20

100% = 40

Which equation represents how to determine the speed of an object?

Answers

The equation that the speed of an object is speed = distance/time

How to determine the equation of an object

From the question, we have the following parameters that can be used in our computation:

Parameter = Object

Argument = Speed

By definition, the speed of an object is the ratio of the distance moved by the object and the time travelled by the object

Mathematically, this can be represented as

Speed = Distance : Time

Express as fraction

Speed = Distance/Time

Hence, the equation is Speed = Distance/Time

Read more about speed at

https://brainly.com/question/14335655

#SPJ1

Show the work please! Thanks!!

Answers

Simplifying

2x + 5y = 2

Solving

2x + 5y = 2

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-5y' to each side of the equation.

2x + 5y + -5y = 2 + -5y

Combine like terms: 5y + -5y = 0

2x + 0 = 2 + -5y

2x = 2 + -5y

Divide each side by '2'.

x = 1 + -2.5y

Simplifying

x = 1 + -2.5y

Simplifying

5X + 10y = 17

Solving

5X + 10y = 17

Solving for variable 'X'.

Move all terms containing X to the left, all other terms to the right.

Add '-10y' to each side of the equation.

5X + 10y + -10y = 17 + -10y

Combine like terms: 10y + -10y = 0

5X + 0 = 17 + -10y

5X = 17 + -10y

Divide each side by '5'.

X = 3.4 + -2y

Simplifying

X = 3.4 + -2y

Determine the equation of the parabola with vertex (7,4) and a directrix y=10.

Answers

The name "parabola" is due to Apollonius, who discovered many properties of conic sections. It means "application",

What is the parabola?pa·​rab·​o·​la pə-ˈrab-ə-lə : a curve formed by the intersection of a cone with a plane parallel to a straight line in its surface : a curve formed by a point moving so that its distance from a fixed point is equal to its distance from a fixed line. : something that is bowl-shaped.This form is called the standard form of a quadratic function. The graph of the quadratic function is a U-shaped curve is called a parabola. The graph of the equation y=x2, shown below, is a parabola.The general equation of a parabola is: y = a(x-h)2 + k or x = a(y-k)2 +h, where (h,k) denotes the vertex. The standard equation of a regular parabola is y2 = 4ax. Some of the important terms below are helpful to understand the features and parts of a parabola.

The equation of the parabola with vertex (-8,5) and directrix y= -3 is given by .

It is given to us that -

The vertex of the parabola = (-8,5)

The directrix of the parabola is y = -3

We have to find the equation of the parabola with the given vertex and directrix.

We know that any point on a given parabola represented as () is equidistant from the directrix and the focus.

So, the equation for the point can be represented as

[tex][y-(-3)]=\sqrt{([x-(-8} ]^{2} +(y-5)^{2}[/tex]

[tex](y+3)^2} =(x+8)^{2} +(y-5)^{2} \\=y^{2}+9+2*y*3=(x+8)^{2} +y^{2}+25-2*y*(-5)=6y-10y=(x+8)^{2} +16=-4y=(xx+8)^{2} +16=y=\frac{-1}{4} (x+8)^{2}+4[/tex]

Thus, the equation of the parabola with vertex (-8,5) and directrix y= -3 is given by .[tex]=y=\frac{-1}{4} (x+8)^{2} +4[/tex]

To learn more about parabola visit

brainly.com/question/4074088

#SPJ1

PLEASE HELP ASAP!!!!!! I WILL GIVE BRAINIEST!!!!! I only need 2 and 3. Please explain your answer so I can understand this!!

Answers

The least expensive per pound is Customer A.

How to illustrate the expression?

It should be noted that expression simply refers to the mathematical statements which have at least two terms which are related by an operator and contain either numbers, variables, or both. Addition, subtraction, multiplication, and division are all possible mathematical operations.

The rate for the first customer will be:

= $14.50 / 1.75

= $8.29 per pound.

The second Customer rate will be:

= $26.25 / 2.5

= $10.5 per pound

The third Customer will be:

= $5.50 / 0.375

= $14.47 per pound.

Learn more about expressions on;

brainly.com/question/723406

#SPJ1

Consider the system of equations

5x+3y=30

−5x−2y=−25

Part A: Solve the system. Show your work.


Part B: Use the solution to your equation to find the value of x – y. Show your work.

x−y =

Answers

The solution for the system of equations is the point (3, 5), and the difference x - y gives:

x - y = -2

How to solve the system of equations?

Here we have the following system of equations:

5x + 3y = 30

-5x - 2y = -25

Notice that in the two equations we have the "5x", but in one case is positive and in the other negative, then we can just add them so we get:

(5x + 3y) + (-5x - 2y) = 30 - 25

(5x - 5x) + (3y - 2y) = 5

0 + y = 5

y = 5

So we found the value of y, by evaluating the second linear equation in y = 5 we will get:

-5*x - 2*5 = - 25

-5x = -25 + 2*5

-5x = -25 + 10

-5x = -15

x = -15/-5 = 3

So y = 5 and x = 3, the difference x - y gives:

3 - 5 = -2

Learn more about systems of equations:

https://brainly.com/question/13729904

#SPJ1

Graph the solution to this inequality on the number line. 1/2x−3<−1 3/8

Answers

The solution to the inequality, 1/2x - 3 < -1 3/8, is x < 13/4. See the graph below.

How to Graph the Solution of an Inequality on a Number Line?

Given the inequality, 1/2x - 3 < -1 3/8, solve to find the value of x, which is the solution to the inequality.

1/2x - 3 < -1 3/8 [given]

1/2x - 3 < -11/8

Add 3 to both sides of the equation:

1/2x - 3 + 3 < -11/8 + 3 [addition property of equality]

1/2x < 13/8

Multiply both sides by 2:

1/2x * 2 < 13/8 * 2 [multiplication property of equality]

x < 13/4

The solution to this inequality, x < 13/4 is given in the graph below.

Learn more about the solution of inequality on:

https://brainly.com/question/24372553

#SPJ1

1/2 of a 360
circle in degrees

Answers

Answer:

Step-by-step explanation:

180 because if you add 180 + 180 = 360

The rate of change is how a quantity is changing with respect to a change in another quantity.
True false question.
True
False

Answers

Answer: True

Step-by-step explanation:

The rate of change or the slope is the changes to another quantity with a constant.

Harmony pays $64.00 per month for a base cable package and an additional amount for on-demand programming. Last month, Harmony received a $67.36 cable bill.

$64.00 + x = $67.36

Ignoring sales tax and additional fees, how much did she spend for on-demand programming?
A) $3.36
B) $6.36
C) $70.72
D.) $131.36

Answers

Should be A!!??!!????!!

What is the y-intercept of this line?​

Answers

Answer: b=13

Step-by-step explanation:

This equation is in point-intercept form:  y = mx + b

slope = m = 4/3

y-intercept = b = 13

1/2 - 1/7 =
3/5 - 1/2

Answers

Answer:

1/2 - 1/7 = 5/14

3/5 - 1/2 = 1/10

Step-by-step explanation:

Are any of these numbers linear expressions? 5x+3, 8xy, 14, or 3x^2​

Answers

Answer: 5x+3 is a linear expression

Step-by-step explanation:

The linear expression is y=mx+b

5x +3 has a slope and y-intercept, so it is a linear expression!

8xy is not because it is just a variable

3x^2 is not because it has ^2

Other Questions
What is the solution of the equation?:-2(3x+1)-2x=-4(2x)-4 The basic unit of the skeletal muscle isQuestion options:A) the fasciculiB) the muscle fiberC) the muscular fasciaD) the endomysium In German, write three sentences describing what you think you personally need in your life. Then write three sentences describing what you want in your life.Be sure to use 6 complete German sentences and to conjugate your verbs correctly.brainlyist if you answer!!!! Read each detail from the assignment text. Then, identify whether the detail indicates that the authors purpose is to inform, to entertain, or to persuade.Many Hispanics spoke only Spanish, and most whites spoke only English.He knew he had the courage to blast through tacklers and the toughness to work all day in the beet fields, but this seemed harder.There were only two days before the next game. The diameter of a circle is 12 ft. Find its area to the nearest whole number. 4.0 mol Na reacts with 2.5 mol F2 according to the equation below2Na +F2 -> 2NaF How many moles of NaF form from 2.5 mol F 2 Find the x- and y-intercepts of the graph of -3x + y = 6. State each answer as aninteger or an improper fraction in simplest form. Question:The instructions next to the register state the following: For all purchases less than $400 ask, Would you like to put this on your Barnes preferred customer card? What is the most likely reason for these instructions?A.To build brand recognition with your customersB.To get customers to join the preferred customer programC.To keep credit charges from the bank lowD.To receive more credit charges from the bank Investment income includes gross income from interest, annuities, and royalties not derived in the ordinary course of a trade or business but does not include any income taken into account when calculating income or loss from a passive activity.true Which statement best completes the diagram A NEED ANSWERED ASAPAn ideal gas is at volume V at temperature T. If the volume is doubled at constant pressure and the same amount of gas particles, the temperature will beunchangedhalveddoubledfour times a country in which a multinational company conducts business activities is called the:____. Which command will you choise to convert a column of data into row the nurse is assisting in a disaster caused by a massive tornado that has destroyed much of the community. this disaster will require statewide and federal assistance. what classification would the disaster be? Please select the word from the list that best fits the definition separation of members in society based on certain characteristics. a doctor prescribed 18 cubic centimeters of a certain drug to a patient whose body weight was 120 pounds. if the typical dosage is 2 cubic centimeters per 15 pounds of body weight, by what percent was the prescribed dosage greater than the typical dosage? Consider the function f(x) = (x-x)(x + 5).1. What are the zeroes of f(x)?2. Write f(x) in standard polynomial form. ONolan is going to a carnival that has games and rides. Each game costs $2.50 andeach ride costs $3.50. Nolan spent $52.50 altogether on 17 games and rides. Write asystem of equations that could be used to determine the number of games Nolanplayed and the number of rides Nolan went on. Define the variables that you use towrite the system. If 17.8 mol of Ar gas occupies 102.8 L, how many mL would occupy 64 mol occupy under the same temperature and pressure? Record your answer in scientific notation using 3 significant figures. Help me please must use elimination