Camille set up 15 rows of chairs in the cafeteria for her school's talent competition. In the first 10 rows, she set up 30 chairs on the left side of the middle aisle and x chairs on the right side. In the last 5 rows, she set up 20 chairs on the left side of the middle aisle and y chairs on the right side to make room for the sound crew. Pick all the expressions that represent how many chairs Camille set up.

Total number of chairs for the middle aisle z= 400 + 10x + y

The total number of chairs in the cafeteria would be 3z = 1200 + 30 x+ 3y

Step-by-step explanation:

Let z be the total number of chairs where z= z1+z2

For the 1st ten rows the expression would be

10 ( 30 + x)= z1

For the last 5 rows the expression would be

5 ( 20 + y) = z2

So total number of chairs in the middle aisle would be

z= z1+ z2

z= 10 ( 30 + x)+5 ( 20 + y)

z= 300 + 10x + 100 + y

z= 400 + 10x + y

The total number of chairs in the cafeteria would be z+z+z ( for the 3 aisle right , middle and left)

3z = 3(400 + 10x + y)

3z= 1200 + 30 x+ 3y

the 2 figures are congruent bc if you reflect abcd over the y axis then over the d axis the figures overlap