If you would like to know what is the unit rate, you can calculate this using the following steps:
6 2/5 revolutions ... 2 2/3 seconds
x revolutions = ? ... 1 second
6 2/5 * 1 = 2 2/3 * x
32/5 = 8/3 * x /*3/8
x = 32/5 * 3/8
x = 12/5
x = 2 2/5 revolutions
The correct result would be 2 2/5 revolutions per second.