document.write( "Question 768080: it takes about 1 1/2 hours to go 12 km downstream and 6 hours to return. Find the speed of the boat in still water and the speed of the current. \n" ); document.write( "

Algebra.Com's Answer #468051 by mananth(16946) $\"\"$ $\"About$

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Boat speed speed =x kph
\n" ); document.write( "current speed =y kph
\n" ); document.write( "against current 6 hours
\n" ); document.write( "with current 1.5 hours
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\n" ); document.write( "Distance against 12 miles distance with 12 miles
\n" ); document.write( "t=d/r against current -
\n" ); document.write( "12 / ( x - y )= 6
\n" ); document.write( "6 ( x - y ) = 12
\n" ); document.write( "6 x - 6 y = 12 ....................1
\n" ); document.write( "
\n" ); document.write( "12 / ( x + y )= 1.50
\n" ); document.write( "1.50 ( x + y ) = 12
\n" ); document.write( "1.50 x + 1.50 y = 12 ...............2
\n" ); document.write( "Multiply (1) by 1
\n" ); document.write( "Multiply (2) by 4
\n" ); document.write( "we get
\n" ); document.write( "6.00 x + -6 y = 12
\n" ); document.write( "6.00 x + 6 y = 48
\n" ); document.write( "12 x = 60
\n" ); document.write( "/ 12
\n" ); document.write( "x = 5 kph
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\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "6 x -6 y = 12
\n" ); document.write( "30 -6 y = 12
\n" ); document.write( "-6 y = 12 -30
\n" ); document.write( "-6 y = -18 mph
\n" ); document.write( " y = 3
\n" ); document.write( "Boat speed speed 5 kph
\n" ); document.write( "current speed 3 kph
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\n" ); document.write( "m.ananth@hotmail.ca
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