Two students are canoeing on a river. While heading upstream, they accidentally drop an empty bottle overboard. They then continue paddling for 1.5 h, reaching a point 1.1 Km farther upstream. At this point they realize that the bottle is missing and, driven by ecological awareness, they turn around and head downstream. They catch up with and retrieve the bottle (which has been moving along with the current) 4.1 Km downstream from the turn-around point.
The Attempt at a Solution
I got the speed in the first phase of the problem, (1.1km/1.5h) but don't know where to go from here.