Row, row, row your boat
Mia was rowing upstream one day when her cap blew off into the stream. She failed to notice it was missing until 20 minutes after it blew off. She immediately turned around and recovered the cap 2.4 miles downstream from where it initially blew off. Assume Mia's rowing rate in still water was constant, the rate of the current was constant, and that it took no time to turn around. Find the number of miles per hour in the rate of the current. Express your answer as an exact decimal.