Art, Ben and Cam travel a 10 mile straight path.
They have a bike and a skateboard.
All 3 walk at 5 mph.
Anyone on bike goes 15 mph, on skateboard goes 6 mph.
They leave at same time, and arrive at end of path at same time.
What is shortest possible time?
NO TRICKS like double riding, carrying skateboard while biking...
A true friend steps in when the rest of the world steps out.