It's about the sprockets and chain of a bicycle. The pedal sprocket has a radius of 4 in., the wheel sprocket has a radius of 2 in., and the wheel a radius of 13 in. The cyclist pedals at 36 rpm.
I already figured out that the rotations per minute of the wheel sprocket is 72 rpm, but what is the speed of the bicycle, assuming that the wheel turns at the same rate as the wheel sprocket?