Answer:
Revolution traveled by me = 30Ï€ ft.
Revolution traveled by my friend = 20Ï€ ft.
Difference between revolutions = 10Ï€ ft.
Step-by-step explanation:
In one revolution, I travel 2Ï€(15) = 30Ï€ ft., and my friend travels 2Ï€(10) = 20Ï€ ft., so my revolution is 30Ï€ - 20Ï€, or 10Ï€, ft. longer than my friend's revolution.