The distance between towns M and N is 280km.A car travelled from M- N .The average speed of the lorry is 20km/hr less than that of the car The lorry takes 1hr 10 minutes more than the car to travel from M - N.lf the speed of the lorry is Xkm/hr Find X

since time = distance/speed,

280/(x+20) = 280/x - 7/6
x = 60
check:
280/80 = 3 hr 30 min
280/60 = 4 hr 40 min