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

Example Input: Problem: find the simple interest on rs . 70,000 at 16 2 / 3 % per year for 9 months .
Example Output: 8750

Example Input: Problem: if 1 / ( x + 4 ) + 1 / ( x - 4 ) = 1 / ( x - 4 ) , what is the value of x ?
Example Output: 4

Example Input: Problem: sum of two numbers is 40 and their difference is 4 . the ratio of the numbers is
Example Output:
11 : 9