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

Example Input: Problem: a man whose speed is 4.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 1.5 kmph , find his average speed for the total journey ?
Example Output: 4

Example Input: Problem: a train 140 m long is running at 60 kmph . in how much time wiu it pass a platform 260 m long ?
Example Output: 24 sec

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