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

Question

How far apart are you and your friend after 15 minutes?

Answer 1

You:
108/8 = 13.5 feet a second
13.5 * 15 * 60 = 12,150 feet

Friend:
63/6 = 10.5 feet a second
10.5 * 15 * 60 = 9,450

12,150 + 9,450 = ?

Answer 2

21,600

Answer 3

2,700