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

Ex Input:
Problem: the sum of ages of 5 children born 1 years different each is 30 years . what is the age of the elder child ?

Ex Output:
8


Ex Input:
Problem: a bullet train covers a distance in 50 min , if it runs at a speed of 48 kmph on an average . the speed at which the bullet train must run to reduce the time of journey to 40 min will be .

Ex Output:
60 kmph


Ex Input:
Problem: two trains , one from howrah to patna and the other from patna to howrah , start simultaneously . after they meet , the trains reach their destinations after 25 hours and 81 hours respectively . the ratio of their speeds is :

Ex Output:

9 : 5