document.write( "Question 532666: The speed of a stream is 5 mph. If a boat travels 72 miles downstream in the same time that it takes to travel 36 miles upstream, what is the speed of the boat in still water? \n" ); document.write( "
Algebra.Com's Answer #350894 by stanbon(75887)\"\" \"About 
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The speed of a stream is 5 mph. If a boat travels 72 miles downstream in the same time that it takes to travel 36 miles upstream, what is the speed of the boat in still water?
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\n" ); document.write( "Downstream DATA:
\n" ); document.write( "distance = 72 miles ; rate = b+5 mph ; time = 72/(b+5) hrs.
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\n" ); document.write( "Upstream DATA:
\n" ); document.write( "distance = 36 miles ; rate = b-5 mph ; time = 36/(b-5) hrs
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\n" ); document.write( "Equation:
\n" ); document.write( "time = time
\n" ); document.write( "72(b+5) = 36/(b-5)
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\n" ); document.write( "2/(b+5) = 1/(b-5)
\n" ); document.write( "Cross-multiply to get:
\n" ); document.write( "2b-10 = b+5
\n" ); document.write( "b = 15 mph (speed of the boat in still water)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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