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

Example Input: Problem: if the average ( arithmetic mean ) of a and b is 45 and the average of b and c is 80 , what is the value of c − a ?
Example Output: 60

Example Input: Problem: seed mixture x is 40 percent ryegrass and 60 percent bluegrass by weight ; seed mixture y is 25 percent ryegrass and 75 percent fescue . if a mixture of x and y contains 40 percent ryegrass , what percent of the weight of this mixture is x ?
Example Output: 100 %

Example Input: Problem: find the constant k so that : - x 2 - ( k + 10 ) x - 8 = - ( x - 2 ) ( x - 4 )
Example Output:
16