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

Ex Input:
Problem: find the area of trapezium whose parallel sides are 20 cm and 18 cm long , and the distance between them is 10 cm ?

Ex Output:
190 cm

Ex Input:
Problem: the sum of the even numbers between 1 and n is 89 * 90 , where n is an odd number , then n = ?

Ex Output:
179

Ex Input:
Problem: a tank is filled by 3 pipes a , b , c in 3 hours . pipe c is twice as fast as b and b is twice as fast as a . how much will pipe a alone take to fill the tank ?

Ex Output:
21 h