A car travels 60km east at 40km/h and then 90km west at 60km/h along the same straight highway. Determine (i) the car’s average speed and (ii) the magnitude and direction of its average velocity for the whole trip.
a) 50km/h;50km/h east
b) 40km/h;20km/h west
c) 50km/h;10km/h west
d) 50km/h;0km/h