SOLUTION: a kayaker goes 12 mph in still water. if the river's current is 5 mph how long will it take to go 20 miles upstream?

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Question 542706: a kayaker goes 12 mph in still water. if the river's current is 5 mph how long will it take to go 20 miles upstream?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +c+ = speed of current
Let +k+ = kayaker's speed in still water
Let +t+ = time to go 20 miles upstream
+k+-+c+ = speed going upstream
given:
+c+=+5+ mi/hr
+k+=+12+ mi/hr
-----------
+20+=+%28k+-+c%29%2At+
+20+=+%2812+-+5%29%2At+
+t+=+20+%2F+7+
+t+=+2.857+ hrs
+.857%2A60+=+51+ min
It will take the kayaker 2 hrs and 51 min