SOLUTION: Joann took 20 minutes to drive her boat upstream, coming back at the same boat speed, it took her 15 minutes. If the current in that part of river is 5 km per hr, what was her boat

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Question 27513: Joann took 20 minutes to drive her boat upstream, coming back at the same boat speed, it took her 15 minutes. If the current in that part of river is 5 km per hr, what was her boat speed?
Thank YOU!
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
20 minutes = 1/3hours
15 minutes = 0.25hours.


0.25%2A%28x%2B5%29=%28x-5%29%2F3
0.25x%2B1.25=%28x-5%29%2F3 --> multiply the whole eqution by 3
0.75x%2B3.75=x-5
-0.25=-8.75
x=35


Hence, the speed of the boat was 35mph.
Paul.