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

Example Input: Problem: at what rate percent on simple interest will rs . 750 amount to rs . 900 in 8 years ?
Example Output: 2.5 %

Example Input: Problem: the average score of a cricketer in 2 matches is 60 and in other 3 matches is 50 . then find the average score in all the 5 matches ?
Example Output: 54

Example Input: Problem: a boat can travel with a speed of 22 km / hr in still water . if the speed of the stream is 5 km / hr , find the time taken by the boat to go 108 km downstream
Example Output:
4 hours