Suppose there is a railroad from A to B. Only one train per day runs from A to B and back, and all passenger trips are round trips. The cost of operating the train for each daily round trip is C = 100 + 20x. Each carriage holds 100 passengers. The average benefit function to the railroads is B(x) = 40 0le where x is the number of passengertrips taken. (Note: Average benefit is the benefit per unit of x, or simply B(>