Joe and Kim washed 27 cars in 6 hours. The next day, they had more help and washed twice as many cars in the same amount of time. What was their average car-washing rate on the second day?
A4.5 cars per hour
B5 cars per hour
C6.2 cars per hour
D9 cars per hour
A4.5 cars per hour
B5 cars per hour
C6.2 cars per hour
D9 cars per hour