Answer
220 students received reduced lunch prices last year.
Work Step by Step
A guideline for this problem would be:
Current number of students = Last year number of students + Amount increase in the number of students.
Let x represent the number of students that received reduced lunch prices last year.
So:
253 = x + 15% $\times$ x
253 = x + 0.15x
253 = 1.15x
Divide both sides by 1.15
220 = x
220 students received reduced lunch prices last year.
