Every hour, a machine makes the same number of tennis racquets. If on the 3rd hour of running, the machine has made 240 racquets, and on the 5th hour of running it has made 400 racquets, what is machines production rate? A
80 racquets per hour
B
100 racquets per hour
C
120 racquets per hour
D
140 racquets per hour