Car A travels 180miles in 7 hours
Car A travels 25.7 miles an hour because 180/7 = 25.7
Car B travels 350 miles in 4 hours
Car B travels 87.5 miles an hour because 350/4= 87.5
Car C travels 584 miles in 15 hours
Car C travels 38.9 miles an hour because 584/9 = 38.9
Car B has the fastest average speed