You and a friend start biking in opposite directions from the same point. You travel 108 every 8 seconds. Your friend travels 63 feet every 6 seconds.

a) to the nearest hundredth if a mile, how far apart are you and your friend after 15 minutes?

b) after 20 minutes you take a 5-minute rest, but your friend does not. To the nearest hundredth of a mile, how far apart are you and your friend after 40 minutes?