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

Ex Input:
Problem: two tains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post . if the length of each train be 120 metres , in what time ( in seconds ) will they cross each other travelling in opposite direction ?

Ex Output:
12


Ex Input:
Problem: in a university the average age in an arts class is 21 and average age in technical class is 18 . what is the age average of university if there are 8 arts classes and 5 technical classes ?

Ex Output:
19.85


Ex Input:
Problem: a man sitting in a train which is travelling at 100 kmph observes that a goods train , travelling in opposite direction , takes 9 seconds to pass him . if the goods train is 280 m long , find its speed ?

Ex Output:

12 kmph .