document.write( "Question 151378: Determine the speed of a motorboat in still water and the speed of the river current, if it takes 3 hrs to travel a distance of 45 miles upstream and 2 hrs to travel 50 miles downstream. \n" ); document.write( "
Algebra.Com's Answer #111276 by stanbon(75887)\"\" \"About 
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Determine the speed of a motorboat in still water and the speed of the river current, if it takes 3 hrs to travel a distance of 45 miles upstream and 2 hrs to travel 50 miles downstream.
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\n" ); document.write( "Let speed of boat be \"b\".
\n" ); document.write( "Let speed of current be \"c\".
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\n" ); document.write( "Upstream DATA:
\n" ); document.write( "distance = 45 miles ; time = 3 hrs; rate = 45/3 = 15 mph
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\n" ); document.write( "Downstream DATA:
\n" ); document.write( "distance = 50 miles ; time = 2 hrs; rate = 50/2 = 25 mph
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\n" ); document.write( "EQUATIONS:
\n" ); document.write( "b + c = 25 mph
\n" ); document.write( "b - c = 15 mph
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\n" ); document.write( "Add to get:
\n" ); document.write( "2b = 40
\n" ); document.write( "b = 20 mph (boat speed in still water)
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\n" ); document.write( "Since b + c = 25, c = = 25-20 = 5 mph (current speed)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
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