document.write( "Question 871365: A boat travels downstream 10 miles in 2.5 hrs. The return trip takes 45 minutes. What's the speed of the boat and river? \n" ); document.write( "

Algebra.Com's Answer #525487 by mananth(16946) $\"\"$ $\"About$

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boat speed =x mph
\n" ); document.write( "current speed =y mph
\n" ); document.write( "against current 2.5 hours
\n" ); document.write( "with current 0.75 hours
\n" ); document.write( "
\n" ); document.write( "Distance against 10 miles distance with 10 miles
\n" ); document.write( "t=d/r against current -
\n" ); document.write( "10.00 / ( x - y )= 2.50
\n" ); document.write( "2.50 ( x - y ) = 0.75
\n" ); document.write( "2.50 x - 2.50 y = 10.00 ....................1
\n" ); document.write( "
\n" ); document.write( "10.00 / ( x + y )= 0.75
\n" ); document.write( "0.75 ( x + y ) = 10.00
\n" ); document.write( "0.75 x + 0.75 y = 10.00 ...............2
\n" ); document.write( "Multiply (1) by 0.75
\n" ); document.write( "Multiply (2) by 2.50
\n" ); document.write( "we get
\n" ); document.write( "1.88 x + -1.88 y = 7.50
\n" ); document.write( "1.88 x + 1.88 y = 25.00
\n" ); document.write( "3.75 x = 32.50
\n" ); document.write( "/ 3.75
\n" ); document.write( "x = 8.67 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "2.50 x -2.50 y = 10.00
\n" ); document.write( "21.67 -2.50 -21.67 = 10.00
\n" ); document.write( "-2.50 y = 10.00
\n" ); document.write( "-2.50 y = -11.67 mph
\n" ); document.write( " y = 4.67
\n" ); document.write( "boat speed 8.67 mph
\n" ); document.write( "current speed 4.67 mph
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\n" ); document.write( "m.ananth@hotmail.ca
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