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

Input: Consider Input: Problem: two pipes a and b can separately fill a cistern in 60 minutes and 75 minutes respectively . there is a third pipe in the bottom of the cistern to empty it . if all the three pipes are simultaneously opened , then the cistern is full in 50 minutes . in how much time , the third pipe alone can empty the cistern ?

Output: 100 min

Input: Consider Input: Problem: ? x 12 = 173 x 240

Output: 3460

Input: Consider Input: Problem: find the principle on a certain sum of money at 9 % per annum for 2 2 / 5 years if the amount being rs . 1120 ?
Output: 921.0