The sum of three numbers is 131. the second of three numbers is seven more than twice the first. the third number is 12 less than the first. what equation can be used to solve the problem?
a. x + x + x = 131
b. x + (x + 7) + (x _ 12) = 131
c. x + (2x + 7) + (x _ 12) = 131
d. x + (2x + 7) _ 12 = 131