Answer:
It took him 7.5 hrs to drive home.
Explanation:
The distance is the same, going or returning.
Recall that distance = rate times time.
Here, distance from Andrew's to his sister's is (60 mph)(8 hr) = 480 mi
If distance = rate times time, then time = distance / rate.
Here we have time = 480 mi / 64 mph = 7.5 hrs
It took him 7.5 hrs to drive home.