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

Ex Input:
Problem: one fast typist type some matter in 4 hrs and another slow typist type the same matter in 6 hrs . if both do combine in how much time they will take to finish .

Ex Output:
2 hr 24 mins

Ex Input:
Problem: two trains running in opposite directions cross a man standing on the platform in 37 seconds and 27 seconds respectively and they cross each other in 29 seconds . the ratio of their speeds is :

Ex Output:
1 :

Ex Input:
Problem: a contractor undertook to do a piece of work in 18 days . he employed certain number of laboures but 9 of them were absent from the very first day and the rest could finish the work in only 6 days . find the number of men originally employed ?

Ex Output:
4.5