document.write( "Question 874896: On a weekend outing, Charles rents a motorboat for 10 hours to travel down the river and back. The rental operator tells him to go for 4 hours downstream, leaving 6 hours to return upstream.
\n" ); document.write( "If the river current flows at a speed of 5 mph, how fast must Charles travel in order to return in 10 hours?
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Algebra.Com's Answer #527833 by mananth(16946)\"\" \"About 
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Boat speed speed x mph
\n" ); document.write( "current speed 5 mph
\n" ); document.write( "..
\n" ); document.write( "against current x- 5
\n" ); document.write( "with current x+ 5
\n" ); document.write( "..
\n" ); document.write( "against current 6 hours
\n" ); document.write( "with current 4 hours
\n" ); document.write( "Distance is same. D=r*t
\n" ); document.write( "6 ( x - 5 ) = 4 ( x + 5 )
\n" ); document.write( "6 x - 30 = 4 x + 20
\n" ); document.write( "6 x - 4 x = 30 + 20
\n" ); document.write( "2 x = 50
\n" ); document.write( "/ 2
\n" ); document.write( "x = 25 mph
\n" ); document.write( "Boat speed speed = 25 mph
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