Johnny rode his bicycle down a hill. It took him 15 seconds to ride from the top of the hill to the bottom of the hill. The equation h = -3t + 45 models his height, h, in feet, above the bottom of the hill as a function of the time, t, in seconds, after he started riding down the hill. Part A: What is the average rate of change in Johnny’s height? Part B: What is the height of the hill? Part C: How long will it take Johnny to travel 1/3 of the distance down the hill?