A truck moves 3 km in 30 min and and returns at same distance in 20 min find average speed

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

answer:

c. the third graph