9. During the past week, Mr. Hamilton gave one quiz and one exam to his high school algebra class. It takes Mr. Hamilton of an hour to grade one student's exam and of an hour to grade one
student's quiz. If x represents the number of students that took the quiz and exam, which
equation below could be used to find the y, the total amount of time, in hours, spent grading?
a) y = 6x
b) y = -X
45
c) y = -x
101
d) y = x