Question 388652
A motorboat can go 16 miles downstream on a river in 20 minutes. It takes 30 minutes for this boat to go back upstream the same 16 miles.
Let x = the speed of the boat.
Let y = the speed of the current. 

a. Write an equation for the motion of the motorboat downstream.
x+y = 16/(1/5) = 80 mph  
b. Write an equation for the motion of the motorboat upstream.
x-y = 16/(1/2) = 32 mph
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c. Find the speed of the current. 
Subtract and solve for "y":
2y = 80-32
2y = 48 mph
y = 24 mph (rate of the current)
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Cheers,
Stan H.