Question 215095
It took a patrol boat 5 hours to travel 60km up a river against the current, and 3 hours for the return trip with the current. Find the speed of the boat in still water and the speed of the current. 
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Let rate of the current be "c":
Let speed of the boat be "b":
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Upstream DATA:
time = 5 hrs ; distance = 60 km ; rate = d/t = 60/5 = 12 km/h
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Downstream DATA:
time = 3 hrs ; distance = 60 km ; rate = d/t = 60/3 = 20 km/h
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Equations:
b-c = 12 km/h
b+c = 20 km/h
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Add to get:
2b = 32
b = 16 km/h (speed of the boat in still water)
Substitute into b+c = 20 to get c = 4 km/h (speed of the current)
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Cheers,
Stan H.
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