Answer:
Step-by-step explanation:
the truck mover 3 km one way, 3 km back, so he moves 6 km
one way the truck needs 30 min, on the way back 20 min
so we have 6 km in 50 min
v=distance/time
v one way=3km/30 min=0.1 km/min
v on the way back=3 km/20min=0.15 km/min
v average =0.1+0.15=0.125 km/min
or 7.5 km/hour
