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

Input: Consider Input: Problem: the ratio between the sale price and the cost price of an article is 12 : 7 . what is the ratio between the profit and the cost price of that article ?

Output: 5 : 7

Input: Consider Input: Problem: what is the prime factors ' number of 18 ?

Output: 3

Input: Consider Input: Problem: if a and b are the roots of the equation x 2 - 9 x + 9 = 0 , then the value of a 2 + b 2 is :
Output: 63