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

Ex Input:
Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab .

Ex Output:
3


Ex Input:
Problem: a group of students decided to collect as many paise from each member of group as is the number of members . if the total collection amounts to rs . 46.24 , the number of the member is the group is :

Ex Output:
68


Ex Input:
Problem: in the manufacture of a certain product , 8 percent of the units produced are defective and 5 percent of the defective units are shipped for sale . what percent of the units produced are defective units that are shipped for sale ?

Ex Output:

0.4 %