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: two trains travel in opposite directions at 36 kmph and 45 kmph and a man sitting in slower train passes the faster train in 12 seconds . the length of the faster train is
Example Output: 270 m

Example Input: Problem: simple interest on a certain sum at a certain annual rate of interest is 1 / 9 of the sum . if the numbers representing rate percent and time in years be equal , then the rate of interest is :
Example Output:
3 1 / 3