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

Ex Input:
Problem: the ratio of three numbers is 2 : 3 : 4 and their sum is 180 . the second number of the three numbers is ?

Ex Output:
60

Ex Input:
Problem: 13 buckets of water fill a tank when the capacity of each bucket is 42 litres . how many buckets will be needed to fill the same tank , if the capacity of each bucket is 6 litres ?

Ex Output:
91

Ex Input:
Problem: a particular library has 75 books in a special collection , all of which were in the library at the beginning of the month . these book are occasionally loaned out through an inter - library program . if , by the end of the month , 80 percent of books that were loaned out are returned and there are 69 books in the special collection at that time , how many books of the special collection were loaned out during that month ?

Ex Output:
30