on a trip covering 850 km , a bicyclist travels the first 400 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 = 400 / 20 = 20 hours time 2 = 450 / 15 = 30 hours total time = 50 hours average speed = 850 / 50 = 17 km / hr the answer is c ."
speed(850, add(divide(400, 20), divide(subtract(850, 400), 15)))