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

Example Input: Problem: find the cost of fencing around a circular field of diameter 16 m at the rate of rs . 3 a meter ?
Example Output: 150.84

Example Input: Problem: when the price of a product was decreased by 20 % , the number sold increased by 60 % . what was the effect on the total revenue ?
Example Output: 28 %

Example Input: Problem: what is the measure of the angle y made by the diagonals of the any adjacent sides of a cube .
Example Output:
60