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

Example Input: Problem: a swimmer can swim in still water at 4 km / h . if the speed of the water current is 2 km / h , how many hours will the swimmer take to swim against the current for 5 km ?
Example Output: 2.5

Example Input: Problem: a reduction of 20 % in the price of oil enables a house wife to obtain 4 kgs more for rs . 600 , what is the reduced price for kg ?
Example Output: 30

Example Input: Problem: how many quarters are equal to 4 dollars ?
Example Output:
16