Can someone tell me how to do this?

For #21, x = 35, y = 85

Step-by-step explanation:

For these types of problems, you will simply use to facts.  The sum of the measure of a line is 180 degrees, and alternate angles of crossing lines are equivalent.  With that being said, let's work #21.

We can see that there are two lines, and we are given 2 values to find with 3 possible equations.

[1] ( 2x + 25 ) + y = 180

[2] y + ( 3x - 10 ) = 180

[3] 2x + 25 = 3x - 10

Using any of these equations, we can solve for the variables.  Let's use the 1st and 3rd equations to find x and y.

2x + 25 = 3x - 10

2x + -2x + 25 + 10 = 3x + -2x + -10 + 10

35 = x

Now plug in the value of x to find y:

( 2x + 25 ) + y = 180

( 2(35) + 25 ) + y = 180

( 70 + 25 ) + y = 180

95 + y = 180

y = 85

We can check these values by plugging into the 2nd equation

x = 35 ; y = 85

y + ( 3x - 10 ) = 180

(85) + (3(35) - 10) = 180

85 + ( 105 - 10) = 180

85 + 95 = 180

180 = 180

Thus, we have validated our results and found the values of x and y.

Cheers.

the answer is b

3 1/3 x 2 3/5 = 8 2/3

step-by-step explanation:

just multiply the first number by the second number to get your answer.