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

Ex Input:
Problem: a cycle is bought for rs . 900 and sold for rs . 1080 , find the gain percent ?

Ex Output:
20 %


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: on the first of the year , james invested x dollars at proudstar bank in an account that yields 4 % in interest every quarter year . at the end of the year , during which he made no additional deposits or withdrawals , he had y dollars in the account . if james had invested the same amount in an account which pays interest on a yearly basis , what must the interest rate be for james to have y dollars at the end of the year ?

Ex Output:

16.25 %