9. Which of the following relations represents a function? 1. {(-1,2), (-6,3), (-6,4), (5,6)}
2. {(1,2), (2,3), (3,4), (2,6)}
3. {(1,2), (2,3), (3,4), (5,6)}
4. {(1,2), (2,3), (1,3), (-5,5)}

10. Fran drove m miles in a car she rented. To find R, the total cost of renting the car, she used the following formula

R = 0.5m + 35

What is the dependent variable in the equation?

11. The formula shows that c, the total cost of buying pizzas at Al's restaurant depends on p, the number of pizzas ordered.

c=9p

What is the independent variable in the equation?