Yak travel agency arranges trips for climbing mount everest. for each trip, they charge an initial fee in addition to $0.15 for each vertical meter climbed. for instance, the price for climbing all the way to the summit, which is 3500 meters above the base of the mountain, is $645. let f(d) f(d) denote the fee of a trip f (measured in dollars) as a function of the vertical distance climbed d (measured in meters).