Question 32565
Let the speed of the boat in still water be "b".
Let the speed of the stream be "s".
UPSTREAM DATA:
 distance=24 mi  time= 3 hr.  therefore rate= b-s=24/3=8
DOWNSTREAM DATA:
 distance=36 mi  time= 3 hr. therefore rate= b+s=36/3=12
EQUATION:
 b-s=8
 b+s=12
Add the equations to get 2b=20
      Then b=10 mph (speed of boat in still water)
Substitute to get "s"
 10+s=12
      Then s=2 mph (speed of the stream)
Cheers,
Stan H.