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

Ex Input:
Problem: the population of a bacteria culture doubles every 2 minutes . approximately how many minutes will it take for the population to grow from 1,000 to 300,000 bacteria

Ex Output:
16


Ex Input:
Problem: at what rate percent on simple interest will rs . 750 amount to rs . 900 in 8 years ?

Ex Output:
2.5 %


Ex 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 ?

Ex Output:

90