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

Ex Input:
Problem: a is half good a work man as b and together they finish a job in 14 days . in how many days working alone b finish the job ?

Ex Output:
21


Ex Input:
Problem: a train traveling at 72 kmph crosses a platform in 33 seconds and a man standing on the platform in 18 seconds . what is the length of the platform in meters ?

Ex Output:
300 meters


Ex Input:
Problem: if a sum of money doubles itself in 20 years at simple interest , the ratepercent per annum is

Ex Output:

5


