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

Example Input: Problem: the cost of the paint is rs . 50 per kg . if 1 kg of paint covers 20 sq . ft , how much will it cost to paint outside of a cube having 20 feet each side
Example Output: rs . 6000

Example Input: Problem: how many seconds will a train 120 meters long take to cross a bridge 150 meters long if the speed of the train is 36 kmph ?
Example Output: 27 sec

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