A boat traveled 144 miles downstream and back. The trip downstream took 4 hours. The trip back took 9 hours. Find the speed of the boat in still water and speed of the current.
Let b = rate of the boat.
Let r = rate of the river.
The rate going downstream is b + r.
The rate going upstream is b - r.
rate x time = distance
4(b + r) = 144 ---> b + r = 36 [divide both sides by 4]
9(b - r) = 144 ---> b - r = 16 [divide both sides by 9]
Add town: 2b = 52
Divide by : b = 26 mi/hr
r = 10 mi/hr