Question 972636
Bill can travel 36 miles upstream in his hovercraft in 3 hours.  If he can return in 2 hours, how fast can Mr. Compton travel in still water? 
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A hovercraft is affected only slightly, if at all, by the current.  It's definitely not a linear function.
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If this were a boat:
Find the 2 speeds, upstream and downstream.
To find miles per hour, divide the miles by the hours.
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His water speed is the average of the 2 speeds.