The task is to generate the correct answer for a given math problem.

Input: Consider Input: Problem: a father said to his son , ` ` i was as old as you are at the present at the time of your birth ' ' . if the father ' s age is 52 years now , the son ' s age 5 years back was :

Output: d ) 21


Input: Consider Input: Problem: what will be the percentage increase in the area of the cube ' s surface if each of the cube ' s edges grows by 20 % ?

Output: 44 %


Input: Consider Input: Problem: for each of her sales , a saleswoman receives a commission equal to 20 percent of the first $ 500 of the total amount of the sale , plus 50 percent of the total amount in excess of $ 500 . if the total amount of one of her sales was $ 800 , the saleswoman ’ s commission was approximately what percent of the total amount of the sale ?


Output: 31