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

Example Input: Problem: the total age of a and b is 12 years more than the total age of b and c . c is how many year younger than a
Example Output: 12

Example Input: Problem: a statue is being carved by a sculptor . the original piece of marble weighed 180 kg . in the first week 28 percent is cut away . in the second week 18 percent of the remainder is cut away . in the third week the statue is completed when 20 percent of the remainder is cut away . what is the weight of the final statue ?
Example Output: 85 kg

Example Input: Problem: selling an kite for rs . 30 , a shop keeper gains 25 % . during a clearance sale , the shopkeeper allows a discount of 10 % on the marked price . his gain percent during the sale is ?
Example Output:
12.5 %