There are 6 roads between Plattsburgh and Lake Placid In how many different ways can a person travel from to back Plattsburgh?

To return to Plattsburgh, a person must travel each of the 6 roads twice. Since the order in which the roads are traveled does not matter, the number of different ways a person can travel from Plattsburgh to Lake Placid and back is

$$6 \times 6 = 36 \ ways.$$