Charles and Carlota are riding bikes up a hill. The first part of the trail is rough, so they ride at a slow constant rate for 20 minutes. Halfway up, they stop and rest for 5 minutes. Then they continue at a slightly faster constant rate for 15 minutes. After reaching the highest part of the trail, they immediately ride down at a constant rate and reach the bottom in only 15 minutes. Sketch a graph of Charles and Carlota's distance from the bottom of the hill as a function of time.