document.write( "Question 731646: Jenny can row 20 miles with the current in 2 hours, or 12 miles against the current in 3 hours. Find the rate of Jenny's boat in still water and the rate of the current. \n" ); document.write( "

Algebra.Com's Answer #447217 by mananth(16946) $\"\"$ $\"About$

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rowing speed =x mph
\n" ); document.write( "current speed =y mph
\n" ); document.write( "against current 3 hours
\n" ); document.write( "with current 2 hours
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\n" ); document.write( "Distance with current 20 miles distance against current 12
\n" ); document.write( "t=d/r against current (x-y)
\n" ); document.write( "12.00 / ( x - y )= 3.00
\n" ); document.write( "
\n" ); document.write( "3.00 x - -3.00 y = 12.00 ....................1
\n" ); document.write( "with current (x+y)
\n" ); document.write( "20.00 / ( x + y )= 2.00
\n" ); document.write( "2.00 ( x + y ) = 20.00
\n" ); document.write( "2.00 x + 2.00 y = 20.00 ...............2
\n" ); document.write( "Multiply (1) by 2.00
\n" ); document.write( "Multiply (2) by 3.00
\n" ); document.write( "we get 2.00
\n" ); document.write( "6.00 x + -6.00 y = 24.00
\n" ); document.write( "6.00 x + 6.00 y = 60.00
\n" ); document.write( "12.00 x = 84.00
\n" ); document.write( "/ 12.00
\n" ); document.write( "x = 7 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1) y
\n" ); document.write( "3 x -3 y = 12
\n" ); document.write( "21 -3 -21 = 12
\n" ); document.write( "-3 y = 12
\n" ); document.write( "-3 y = -9 mph
\n" ); document.write( " y = 3
\n" ); document.write( "rowing 7 mph
\n" ); document.write( "current 3 mph
\n" ); document.write( " \n" ); document.write( "

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