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

Ex Input:
Problem: mary can do a piece of work in 26 days . rosy is 30 % more efficient than mary . the number of days taken by rosy to do the same piece of work is ?

Ex Output:
20


Ex Input:
Problem: find the simple interest on rs . 70,000 at 16 2 / 3 % per year for 9 months .

Ex Output:
8750


Ex Input:
Problem: the cost to park a car in a certain parking garage is $ 10.00 for up to 2 hours of parking and $ 1.75 for each hour in excess of 2 hours . what is the average ( arithmetic mean ) cost per hour to park a car in the parking garage for 9 hours ?

Ex Output:

$ 2.47