Driving 60mph for 3 hours would see Jen and her parents cover
60 * 3 = 180 miles
Driving 40mph for 3 hours would see Jen and her parents cover
40 * 3 = 120 miles
The total distance covered would be;
180 + 120 = 300 miles
If they covered the same distance for the same time (that is 3 + 3 = 6 hours), then the average speed that Jen and her parents used on the way back is;
