a boat took 2 hrs to make a downstream trip w a 5mph current.?

Question

the return trip against the same current took 4 hours. find the speed of the boat in still water

Answer 1

Distance = Rate x Time

Let S be the speed of the boat in still water and C be the speed of the current.

Leg 1: D = ( S + C ) ( 2 hours )
Leg 2: D = ( S - C ) ( 4 hours )

Set them equal:

( S + C ) ( 2 hours ) = ( S - C ) ( 4 hours )

Plug in 5 mph for C and solve for S in mph.