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

Ex Input:
Problem: a starts business with rs . 3500 and after 8 months , b joins with a as his partner . after a year , the profit is divided in the ratio 2 : 3 . what is b â € ™ s contribution in the capital ?

Ex Output:
15750


Ex Input:
Problem: the probability is 1 / 2 that a certain coin turns up heads on any given toss . if the coin is tossed 6 times , what is the probability that the coin turns up tails on at least one of the tosses ?

Ex Output:
63 / 64


Ex Input:
Problem: when positive integer n is divided by 3 , the remainder is 1 . when n is divided by 7 , the remainder is 5 . what is the smallest positive integer k such that k + n is a multiple of 21 ?

Ex Output:

2