on a trip covering 450 km , a bicyclist travels the first 300 km at 20 km per hour and the remainder of the distance at 15 km per hour . what is the average speed , in km per hour , for the entire trip ?
"time 1 = 300 / 20 = 15 hours time 2 = 150 / 15 = 10 hours total time = 25 hours average speed = 450 / 25 = 18 km / hr the answer is d ."
speed(450, add(divide(300, 20), divide(subtract(450, 300), 15)))