greg rides his motorized scooter for 20 minutes. greg starts riding at 0 mph. greg's maximum speed is 35 mph, which he reaches 5 minutes after he starts riding. greg's speed increases steadily for 5 minutes. at the 10-minute mark, greg decreases his speed for 2.5 minutes, then he stays at 20 mph for 5 minutes. at the 17.5-minute mark, he again decreases his speed for 2.5 minutes until he stops. use the key features to sketch a graph