Question 764768
After rowing upstream for exactly one mile the wind kicked up and blew
Captain America’s hat into the water, where it began floating downstream. 
Captain America continued rowing upstream.
 However, after 10 minutes of rowing he remembered that he had left
 his secret decoder ring in the inside pocket of the hat, so he changed
 direction and began rowing downstream at exactly the same intensity
 with which he had been rowing upstream.
 He caught up with his hat at the dock where he had put the boat in
 the water.
How fast was the current moving?
:
The boat and the hat are in the same moving water so the current does
not affect their relationship. If he rowed for 10 min away, it will take
him 10 min to row back to the hat, however the their frame of ref
traveled 1 mile in this 20 min time, therefore
1 mi in 20 min = 3 mph, the speed of the current