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

Ex Input:
Problem: if 4 xz + yw = 10 and xw + yz = 20 , what is the value of the expression ( 2 x + y ) ( 2 z + w ) ?

Ex Output:
50 .

Ex Input:
Problem: the total age of a and b is 12 years more than the total age of b and c . c is how many year younger than a

Ex Output:
12

Ex Input:
Problem: what is the greatest integer m for which the number 50 ! / 10 ^ m is an integer ?

Ex Output:
1