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

Input: Consider 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 .

Output: 60 kmph


Input: Consider Input: Problem: a man can do a piece of work in 7 days , but with the help of his son , he can finish it in 3 days . in what time can the son do it alone ?

Output: 4 1 / 5


Input: Consider Input: Problem: the sum of the ages of 4 children born at the intervals of 1 years each is 12 years . what is the age of the youngest child ?


Output: 1.5