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

Example Input: Problem: three 7 faced dice are thrown together . the probability that all the three show the same number on them is ?
Example Output: 1 / 49

Example Input: Problem: two trains , a and b , started simultaneously from opposite ends of a 125 - mile route and traveled toward each other on parallel tracks . train a , traveling at a constant rate , completed the 125 - mile trip in 12 hours ; train b , traveling at a constant rate , completed the 125 - mile trip in 8 hours . how many miles had train a traveled when it met train b ?
Example Output: 5

Example Input: Problem: a walks at 10 kmph and 4 hours after his start , b cycles after him at 20 kmph . how far from the start does b catch up with a ?
Example Output:
80 km