9. Given the two functions: f(x) = x -3 and g(x) =_ X a) Find (fog) (x) and its domain. b) Find g(a + 2) c) Find (fg) (x) and its domain d) Find g(g(f(2)) 10. On a certain route, an airline carries 6000 passengers per month, each paying $110. A market survey indicates that for each $1 decrease in the ticket price, the airline will gain 40 passengers. a) Express the number of passengers per month, N, as a function of the ticket price, x. b) Express the monthly revenue for the route, R, as a function of the ticket price, x. 11. You have 800 feet of fencing to enclose a rectangular field. Express the area of the field A(x), as a function of its length, x. 12. Suppose that a ball is rolling down a ramp. The distance traveled by the ball is given by the function s(t), where t is the time, in seconds, after the ball is released, and s(t) is measured in feet. For the given function, find the ball's average velocity (rate of change) from t1 to t2. s(t) = 11t2 + 6t , t1 = 3 t2 = 3.5