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

Example Input: Problem: how many diagonals does a polygon with 13 sides have , if one of its vertices does not connect to any diagonal ?
Example Output: 54

Example Input: Problem: the average weight of a , b and c is 60 kg . if the average weight of a and b be 70 kg and that of b and c be 50 kg , then the weight of b is :
Example Output: 60 kg

Example Input: Problem: if a = 105 and a ^ 3 = 21 × 25 × 45 × z , what is the value of z ?
Example Output:
49