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

Ex Input:
Problem: pipe a can fill a tank in 6 hours . due to a leak at the bottom , it takes 10 hours for the pipe a to fill the tank . in what time can the leak alone empty the full tank ?

Ex Output:
15


Ex Input:
Problem: if | 5 x - 20 | = 100 , then find the sum of the values of x ?

Ex Output:
8


Ex Input:
Problem: in an election between two candidates , one got 60 % of the total valid votes , 30 % of the votes were invalid . if the total number of votes was 9000 , the number of valid votes that the other candidate got , was :

Ex Output:

2520