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

Example Input: Problem: given that p is a positive even integer with a positive units digit , if the units digit of p ^ 3 minus the units digit of p ^ 2 is equal to 0 , what is the units digit of p + 4 ?
Example Output: 10

Example Input: Problem: find compound interest on $ 10000 at 15 % per annum for 2 years 4 months , compounded annually .
Example Output: 3886.25

Example Input: Problem: the average of the marks of 25 students in a class is 70 . if the marks of each student are doubled , find the new average ?
Example Output:
140