Answer:
speed in still water = 9 mph
total time = 12 hours
Explanation:
speed = distance/time
distance = speed * time
Traveling downstream:
speed of river = 3 mph
speed of canoe in still water = v
speed of canoe going downstream = v + 3
distance = 96/2 = 48
time = t
distance = speed * time
48 = (v + 3)(t)
Traveling upstream:
speed of river = 3 mph
speed of canoe in still water = v
speed of canoe going downstream = v - 3
distance = 96/2 = 48
time = 2t
distance = speed * time
48 - d = (v - 3)(2t)
48 = (v + 3)(t)
48 = (v - 3)(2t)
vt + 3t = 48
2vt - 6t = 48
-2vt - 6t = -96
(+) 2vt - 6t = 48
------------------------
-12t = -48
t = 4
vt + 3t = 48
4v + 3(4) = 48
4v + 12 = 48
4v = 36
v = 9
speed in still water = v = 9 mph
total time = t + 2t = 3t = 3(4) = 12 hours