SOLUTION: Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4-mph current, it took her 20 minutes longer to get their than to return. How fast will her bo

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Let = her speed in still water
Let = the speed of the current
Let = the distance she has to go
Let = time going upstream in hrs
Let = time going downstream in hrs
Then
= speed of boat going upstream
= speed of boat going downstream
----------------
The problem says
mi/hr

mi
----------------
going upstream


and, going downstream


Substitute this into the upstream equation

Multiply both sides by





mi/hr
The speed of the boat in still water is 11.662 mi/hr
check answer:






hrs

hrs
going upstream

close enough
also


close enough