The three riders after reflecting on the situation form the opinion that only the costs for gasoline, oil & lubrication, tires and repairs are a function of mileage driven (variable costs) and thus could be caused by the trip. Since these four costs total only $0.198 per mile and, therefore, $158.40 for the 800-mile trip, the share for each student would be $158.40/3 = $52.80. Obviously, the opposing views are substantially different