A major airline purchases a particular type of plane at a cost of $40,000,000. The company estimates that the average capital cost and average operating costs are a function of x, the number of hours of flight time. The salvage value of a plane (in dollars) is expressed by the function. () = 36,000,000 − 10,000 Average operating cost, stated in dollars per hour of flight time, is estimated by the function. () = 500 + 0.40 a) Determine how many hours a plane should be flown before replacement if the objective is to minimize the sum of average capital cost and average operating cost per hour.