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

Ex Input:
Problem: the curved surface of a sphere is 64 cm 2 . find its radius ?

Ex Output:
4', 'd ) 9', 'e ) 7'

Ex Input:
Problem: the compound interest on $ 30,000 at 7 % p . a is $ . 4347 . find out the period ( in years ) ?

Ex Output:
2

Ex Input:
Problem: in a garden , 26 trees are planted at equal distances along a yard 700 metres long , one tree being at each end of the yard . what is the distance between two consecutive trees ?

Ex Output:
28