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

Ex Input:
Problem: find the principle on a certain sum of money at 9 % per annum for 2 2 / 5 years if the amount being rs . 1120 ?

Ex Output:
921.0


Ex Input:
Problem: by investing in 1623 % stock at 64 , one earns rs . 1500 . the investment made is

Ex Output:
rs . 5760


Ex Input:
Problem: how many integers k greater than 100 and less than 700 are there such that if the hundreds and the unit digits of k are reversed , the resulting integer is k + 99 ?

Ex Output:

50