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

Ex Input:
Problem: calculate the sum of first 60 natural numbers .

Ex Output:
1830

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 part of certain sum of money is invested at 16 % per annum and the rest at 20 % per annum , if the interest earned in each case for the same period is equal , then ratio of the sums invested is ?

Ex Output:
5 :