SOLUTION: Jason is driving a boat against the 5 mph current for 3 hours. then, he drives back, which takes 1.5 hours. how fast would he travel in still water?

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Question 721688: Jason is driving a boat against the 5 mph current for 3 hours. then, he drives back, which takes 1.5 hours. how fast would he travel in still water?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = the speed of the boat in still water in mi/hr
+s+%2B+5+ = his speed going with the current in mi/hr
+s+-+5+ = his speed going against the current in mi/hr
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Against the current:
+d+=+%28+s+-+5+%29%2A3+
+d+=+%28+s+%2B+5+%29%2A1.5+
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By substitution:
+%28+s+-+5+%29%2A3+=+%28+s+%2B+5+%29%2A1.5+
+3s+-+15+=+1.5s+%2B+7.5+
+1.5s+=+22.5+
+s+=+15+
He would travel 15 mi/hr in still water