Evelyn 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 Evelyn set up.
To calculate the total number of chairs, we need to consider the number of rows and the number of chairs in each side of the rows.
For the first 10 rows:
- 30 chairs on the left side
- x chairs on the right side
Thus, for each of the first 10 rows, she set up a total of (30 + x) chairs, and since there are 10 of these rows, the expression representing the chairs in the first 10 rows is:
10 * (30 + x) = 300 + 10x
For the last 5 rows:
- 20 chairs on the left side
- y chairs on the right side
So for each of the last 5 rows, she set up a total of (20 + y) chairs, and since there are 5 of these rows, the expression representing the chairs in the last 5 rows is:
5 * (20 + y) = 100 + 5y
The total number of chairs that Evelyn set up is the sum of the chairs in the first 10 rows and the last 5 rows, therefore the expression representing the total number of chairs is:
(300 + 10x) + (100 + 5y) = 300 + 100 + 10x + 5y = 400 + 10x + 5y
In other words, the expression to represent the number of chairs Evelyn set up is:
400 + 10x + 5y