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

Ex Input:
Problem: one half of a two digit number exceeds its one third by 7 . what is the sum of the digits of the number ?

Ex Output:
e ) 1


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

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


Ex Input:
Problem: if 15 students in a class average 75 % on an exam and 10 students average 90 % on the same exam , what is the average in percent for all 25 students ?

Ex Output:

81 %