A saleman took 1/2h to drive from Tuas to Bedok at an average speed of 72km/h.when he returned from Bedok to Tuas,he travelled at an average speed of 90km/h along the same road.how long did the salesman take to reach Tuas?
d = r*t =72km/h * 0.5h = 36 km.
d = r*t.
t = d/r = 36km / 90km/h = 0.4 h.