Answer:
Average speed is distance/time. You could say, 12/6 = 2 miles per second and say that’s the answer, but we relate to mph so much better. Since there are 60 x 60 = 3600 sec in an hour, that same speed is:
2 x 3600 = 7,200 mph
No “car” can travel this fast. Some rocket cars have gone about 1/10th this speed.