document.write( "Question 58777This question is from textbook Elementry and Intermediate algebra
\n" ); document.write( ": John can run his boat in the still water at a speed of 15 miles per hour. If he can go 12 miles downstream in the same time as it takes him to go 9 miles upstream, then what is the speed of the water currents? \n" ); document.write( "
Algebra.Com's Answer #40307 by stanbon(75887)\"\" \"About 
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John can run his boat in the still water at a speed of 15 miles per hour. If he can go 12 miles downstream in the same time as it takes him to go 9 miles upstream, then what is the speed of the water currents?
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\n" ); document.write( "Let speed of the current be \"c\".
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\n" ); document.write( "Downstream DATA:
\n" ); document.write( "distance = 12 mi. ; Rate = 15+c mph ; time=d/r=12/(15+c) hrs.
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\n" ); document.write( "Upstream DATA:
\n" ); document.write( "distance =9mi ; rate = 15-c ; time = d/r= 9/(15-c)
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\n" ); document.write( "EQUATION:
\n" ); document.write( "time down = time up
\n" ); document.write( "12/(15+c) = 9/(15-c)
\n" ); document.write( "12(15-c)=9(15+c)
\n" ); document.write( "180-12c=135+9c
\n" ); document.write( "45=21c
\n" ); document.write( "current speed =15/7= 2.15 mph
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.\r
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