Answer:
below
Explanation:
I'm not absolutely know what are you asking for the answer, but this graph shows ...
The first 20 minutes he has a constant speed of 1.8/20=0.09 km/min progress to 1.8 km away from home, then has 10 minutes (from 20-30) stop at the spot.
Then he drive home with speed of 0.045 km/min (1.8/40=0.045) for 40 minutes to return to the start point.