Question 248519
A boat travels 60 km upstream (against the current) in 5 hours.
Upstream DATA:
distance = 60 km ; time = 5 hrs ; rate = distance/time = 60/5 = 12 mph
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The boat travels the same distance downstream in 3 hours.
Downstream DATA:
distance = 60 km ; time = 3 hrs ; rate = d/t = 60/3 = 20 mph
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What is the rate of the boat in still water? 
What is the rate of the current?
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Let the rate of the boat in still water be "b"
Let the rate of the current be "c".
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Equations:
b + c = 20 mph
b - c = 12 mph
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Add the equation and solve for "b":
2b = 32
b = 16 mph (rate of the boat in still water)
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Substitute b=16 into b+c = 20 to solve for "c":
16 + c = 20
c = 4 mph (rate of the current)
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Cheers,
Stan H.