The pedals may be thought of as the input . This input is sent to the chain function, say which is then sent to the wheel function, say . This can be thought of as the composition of functions, . Which means the values we found were & .
Find the rate of change of the pedals with respect to the chain, the rate of change of the chain with respect to the wheel, and the rate of change of the pedals with respect to the wheel. See if you can find a relationship between these values.