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

Example Input: Problem: the average of first six prime numbers greater than 20 is ?
Example Output: 3

Example Input: Problem: a student chose a number , multiplied it by 2 , then subtracted 138 from the result and got 102 . what was the number he chose ?
Example Output: 120

Example Input: Problem: what is the value of n if the sum of the consecutive odd intergers y from 1 to n equals 169 ?
Example Output:
25