The total points for a test is 156 and there are 15 questions. Each question is worth 6 points or 12 points.
a) Let x be the number of 6–point questions and
Let y be the number of 12–point questions.
Write a system of equations to find the number of each type of question.
b) Solve the system by graphing.
c) How many questions of each type are on the test?