25 PTS: This is pretty simple, I tried to ask my maths teacger for help but she was very vague and i am still stuck.

x = total age of boys

x / 30 = 11yrs

Multiply both sides by 30

x = 330

y = total age of girls

y / 20 = 12

Multiply both sides by 20

y = 240

(240 + 330) / 50 = 11.4 yrs

The average age of the whole class = 11.4 years.

A class has 30 boys and 20 girls.

The average age of boys and girls is 11 and 12 respectively.

The average age of the whole class.

Boys = No. of boys × Age

Boys = 30 × 11 = 330

Girls = No. of girls × Age

Girls = 20 × 12 = 240

Average Age = Boys + Girls / Total no. of boys and girls

Average Age = 330 + 240 / 50

Average Age = 570 / 50

Average Age = 11.4

Average age of of the whole class is 11.4 .

Answer:

A

Step-by-step explanation:

because it is is parenthesis

Answer:

His average speed is 4.75 m/s

Step-by-step explanation:

Here, we are interested in calculating the average speed of the boy.

At time t = 4 seconds, total distance traveled = 6 meters

The average speed here is distance/time = 6/4 = 1.5 m/s

Now at time 30 7 seconds , he has rolled 30 meters

What this actually means is that for the next 3 seconds after the initial 4 seconds, he rolled a total distance of 30-6 = 24 meters. Hence, he rolled 24 meters in the next three seconds

So mathematically, his average speed for the second part of the rolling is 24/3 = 8 meters per second

Conclusively therefore , his average speed will be (1.5 + 8)/2 = 9.5/2 = 4.75 meters per second

Answer:

Perimeter: 42cm

Area: 66cm^2

Step-by-step explanation:

Answer:

P42 cm - P26 cm = 16 cm + 13 cm = P = 26 cm

Step-by-step explanation:

Those are two rectangles. One total and deduct the missing piece.

P=2(l+w)

First: Total 12 by 9 rectangles = P42 cm

Second: Lengths = 12 -5 = 7 and 9-3 = 6 = P=26

Thirs: add the missing lengts! 7 + 6 cm

Answer:

7x for the first expression

2x + 2y + 8x^2

Step-by-step explanation:

5(2x) - 3x

= 10x - 3x = 7x

2x + 2y + x^2(8)

= 2x + 2y + 8x^2

Definitions:

A number, x, is even if it satisfies: x = 2n for some integer n

A number, x, is odd if it satisfies: x = 2k+1 for some integer k

Rewriting the Question:

In this case the question is asking if there is a number, x, that is has the following property:

x = 2n for some integer n AND x = 2k+1 for some integer k

Proof:

We can set these two equations equal:

2n = x = 2k + 1

2n = 2k + 1

2n - 2k = 1

2(n - k) = 1

Let number y = n - k. Note that since n and k are integers, n-k (and therefore, y) must also be an integer.

2y = 1

You can see on the left side (2y) that this becomes the definition of an even number! So the left side is an even number and the right side is 1. Since we know by definition that 1 is not an even number and k must be an integer (not 0.5), this equation becomes false.

As a result, there are NO numbers that can be both even AND odd.

Answer:

m<DAE = 80°

Step-by-step explanation:

Given that m<CAB = 110°,

m<DAE = (x + 4)°,

m<EAF = 30°,

m<EAF + m<DAE = m<DAF (angle addition postulate)

30° + (x + 4)° = m<DAF (substitution)

(34 + x)° = m<DAF

<DAF and <CAB are vertically opposite angles. Vertically opposite angles are said to be congruent. Therefore:

m<DAF = m<CAB

(34 + x)° = 110° (substitution)

The equation above can be used to solve for x as follows:

34 + x = 110

x = 110 - 34 (Subtracting 34 from both sides)

x = 76

m<DAE = (x + 4)°

Plug in 76, to replace x

m<DAE = 76 + 4

m<DAE = 80°

Answer:

9.99

Step-by-step explanation:

Answer: C

Step-by-step explanation:

To find f(g(x)), you plug in g(x) into f(x).

[tex]f(g(x))=\sqrt{(8x-12)+8}[/tex]                [combine like terms]

[tex]f(g(x))=\sqrt{8x-4}[/tex]                           [factor]

[tex]f(g(x))=\sqrt{4(2x-1)}[/tex]                      [square root of 4]

[tex]f(g(x))=2\sqrt{2x-1}[/tex]

Now, we know that the answer is C.

Answer:

x = 4

Step-by-step explanation:

-16 = -5x + x   -->   Collect like terms   -->    -16 = -4x    -->

                   swap the sides of the equation   4x = -16   -->  

   Divide both sides of the equation by -4   -->      x =4  

Answer: C or $256

You will also save $64

Answer:

The cost of the stereo system is $256.

Step-by-step explanation:

What we know:

The cost of the stereo system is $320.

Zenaida is getting the stereo system 20% off.

We can set our equation up like this:

Stereo System = 320-320*20%

(to find the cost of the stereo system, we have to subtract 20% of the original price)

1. Multiply 20 by 100 to change 20% into a decimal

20*100=0.2

2. Plug into the equation and solve

320-320*0.2

= 320-64

= 256

I hope this helped!

Answer: -36 is your answer

Step-by-step explanation:

Answer:

7x+y, when x+4 and y+5

7(4) + 5=

28+5=

33

Step-by-step explanation:

Hope this helps. :)

Answer:

shortest side = 3 in

Step-by-step explanation:

Sum the 3 sides and equate to 13, that is

x - 5 + 6 + [tex]\frac{x}{2}[/tex] = 13, that is

x + 1 + [tex]\frac{x}{2}[/tex] = 13 ( subtract 1 from both sides )

x + [tex]\frac{x}{2}[/tex] = 12 ( multiply through by 2 to clear the fraction )

2x + x = 24

3x = 24 ( divide both sides by 3 )

x = 8

Thus

x - 5 = 8 - 5 = 3 and [tex]\frac{x}{2}[/tex] = [tex]\frac{8}{2}[/tex] = 4 , then

The shortest side is x - 5 = 3 in

Answer: [tex]d=\frac{T+N3}{G}[/tex]

Step-by-step explanation:

To solve for d, we want to use algebraic properties to isolate d.

[tex]T=Gd-N3[/tex]            [add both sides by N3]

[tex]T+N3=Gd[/tex]            [divide both sides by G]

[tex]\frac{T+N3}{G} =d[/tex]

[tex]d=\frac{T+N3}{G}[/tex]

Now, we know that [tex]d=\frac{T+N3}{G}[/tex].

Answer:

P = 12

Step-by-step explanation:

Given formula for the perimeter 'P' of a rectangle is,

P = 2L + 2W

If the values of L and W are,

L = 4 and W = 2

Perimeter of the rectangle = 2(L + W)

                                            = 2(4 + 2)

                                            = 2 × 6

                                            = 12 units

Therefore, value of remaining variable 'Perimeter' = 12 units

(There is no use of 'pi' in calculating the perimeter of a rectangle).

Answer:

390

Step-by-step explanation:

100% CORRECT

Answer:

B has a negative exponent: 8 x 10^-7

A doesn't: 4.267 x 10^7

Answer:

Experiment

Step-by-step explanation:

By going out of her way to make different tests and giving it to different portions of the class, she's creating and running an experiment.

Answer: x - 2y + 2z

keep it in alphabetical order!

Step-by-step explanation:

the negative on the outside changes what is on the inside, so the new equation will be

3x + 4y - 2x + 2z - 6y

combine like terms

x - 2y + 2z

Answer: 3x +10y

Step-by-step explanation:

first you put all the common integers (i think that is what they are called) together

3x+4y+6y-2z-(-2z)

Then you add and subtract all the integers

4y+6y=10y

-2z-(-2z)=0

so the answer is

3x+ 10y

Hopefully this is the right answer

God bless you!!

Answer:

I'm trying to find it out to

Step-by-step explanation:

the answer would be 4/four!

Your answer would be four

Answer:

b.  22 feet below sea level.

Hope this helps:)

Step-by-step explanation:

Answer:

60 percent

Step-by-step explanation:

so 50 is half of 100,right? so that means you can just multiply everything by 2 to make it easier. so then there are 100 students and 40 play basket ball. so that means 40 percent play basketball and that only leaves 60 remaining :)

Answer:2.500

Step-by-step explanation:

when rounding up to the nearest hundred you look at the tenths, if the tenths is 50 and above, you round up, when 49 and below, you round down.

Answer:

The equality is false because one side is positive and the other side negative.

Step-by-step explanation:

5(4)+7        

Multiply the numbers 4 and 5

20

20+7

add the numbers 20 and 7

27[tex]\neq[/tex]-3

so the number 4 is not the solution