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?