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

Example Input: Problem: in township k , 1 / 5 of the housing units are equipped with cable television . if 1 / 10 of the housing units , including 1 / 3 of those that are equipped with cable television , are equipped with videocassette recorders , what fraction of the housing units have neither cable television nor videocassette recorders ?
Example Output: 23 / 30

Example Input: Problem: if the sides of a cube are in the ratio 5 : 3 . what is the ratio of their diagonals ?
Example Output: 5 : 3'

Example Input: Problem: how many positive integers less than 100 are there such that they are multiples of 13 or multiples of 12 but not both ?
Example Output:
15