What is the average rate of change of f(x), represented by the table of values, over the interval [-3, 2]?

Average rate of change is:
C) 8

Aand b is what i think

If you need an equation, it would be y=2x+8, y would be how long it grew, x being weeks.if you need how long he was asleep, it would be 4 weeks if he started with no beard, the equation would be x=8÷2if he did have a beard before hand, the equation would be 2w+x=8