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

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


Ex Input:
Problem: a shopkeeper loses 15 % , if an article is sold for rs . 102 . what should be the selling price of the article to gain 20 % ?

Ex Output:
rs . 144


Ex Input:
Problem: the least perfect square , which is divisible by each of 21,36 and 66 is

Ex Output:

213444', 'b ) 214344', 'c ) 214434', 'd ) 213443', 'e ) none of these'