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

Example Input: Problem: how many prime numbers are between 51 / 13 and 89 / 9 ?
Example Output: 2

Example Input: Problem: there are 750 male and female participants in a meeting . half the female participants and one - quarterof the male participants are democrats . one - third of all the participants are democrats . how many of the democrats are female ?
Example Output: 125

Example Input: Problem: of the 200 stamps in a collection , 80 are foreign and 50 are more than 10 years old . if 20 stamps are both foreign and more than 10 years old , how many stamps are neither foreign nor more than 10 years old ?
Example Output:
90