Answer:
1 mi/hr
Step-by-step explanation:
Given that:
Speed in still water, s = 5 mi/hr
Let speed of current = x
Time = distance /speed
Upstream (subtract speed of current) = 5 - x
Upstream time = 8 / 5 - x - - - (1)
Downstream (add speed of current) = 5 + x
Downstream time = 12 / 5 + x - - - (2)
Equate (1) and (2)
8 / (5 - x) = 12/ (5 + x)
8(5 + x) = 12(5-x)
40 + 8x = 60 - 12x
40 - 60 = - 12x - 8x
-20 = - 20x
x = 1
Spwed of current = 1 mi/hr
