Final answer:
Each fifth grader will get to spend $3.50 on lunch.
Step-by-step explanation:
To find out how much each fifth grader will get to spend on lunch, we need to divide the total amount they paid for lunch by the number of students. The total amount paid for lunch is $315 and there are 90 fifth-grade students. So, we can divide $315 by 90 to find the amount each student will get to spend on lunch.
Dividing $315 by 90, we get:
$315 / 90 = $3.50
Therefore, each fifth grader will get to spend $3.50 on lunch.