A vacationer gets into his out-board motorboat and leaves a dock on a river bank for a day of fishing. Just as he turns upstream, he hears a splash but pays no attention and continues cruising at normal speed. 30.0 minutes later he realizes that his watertight lunchbox is missing. He then turns downstream, with the motor still set at cruising speed. He sights his lunchbox floating down the river and retrieves it at a point 0.2 km downstream of the dock. How long after turning around does he pick up his lunch?
v = s/t
The Attempt at a Solution
I can't figure out anything in the problem. I don't know how to set it up.