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

Ex Input:
Problem: a and b can do a work in 5 days and 10 days respectively . a starts the work and b joins him after 2 days . in how many days can they complete the remaining work ?

Ex Output:
2

Ex Input:
Problem: by investing in 1623 % stock at 64 , one earns rs . 1500 . the investment made is

Ex Output:
rs . 5760

Ex Input:
Problem: john has 10 pairs of matched socks . if he loses 3 individual socks , what is the greatest number of pairs of matched socks he can have left ?

Ex Output:
8