A Spectator Watches a Rowing Race from the Edge of a River

Short Answer

A spectator watches a rowing race from the edge of a river bank. The lead boat is moving in a straight line that is 330 ft from the river bank. If the boat is moving at a constant speed of 20 ft/sec, how fast is the boat moving away from the spectator when it is 560 ft past her?
Round the answer to the nearest hundredth, if necessary.
__________ ft/sec