Answer:
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