document.write( "Question 999800: A plane flies 480 miles with the wind in 4 hours. Returning against the wind,
\n" ); document.write( "takes 6 hours. What is the rate of the plane in still air? \n" ); document.write( "

Algebra.Com's Answer #617342 by mananth(16946) $\"\"$ $\"About$

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\n" ); document.write( "Plane speed =x mph
\n" ); document.write( "wind speed =y mph
\n" ); document.write( "against wind 6 hours
\n" ); document.write( "with wind 4 hours
\n" ); document.write( "
\n" ); document.write( "Distance against 480 miles distance with 480 miles
\n" ); document.write( "t=d/r against wind -
\n" ); document.write( "480 / ( x - y )= 6
\n" ); document.write( "6 ( x - y ) = 480
\n" ); document.write( "6 x - 6 y = 480 ....................1
\n" ); document.write( "
\n" ); document.write( "480 / ( x + y )= 4.00
\n" ); document.write( "4.00 ( x + y ) = 480
\n" ); document.write( "4.00 x + 4.00 y = 480 ...............2
\n" ); document.write( "Multiply (1) by 4
\n" ); document.write( "Multiply (2) by 6 24
\n" ); document.write( "we get
\n" ); document.write( "24.00 x + -24 y = 1920
\n" ); document.write( "24.00 x + 24 y = 2880
\n" ); document.write( "48 x = 4800
\n" ); document.write( "/ 48
\n" ); document.write( "x = 100 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "6 x -6 y = 480
\n" ); document.write( "600 -6 y = 480
\n" ); document.write( "-6 y = 480 -600
\n" ); document.write( "-6 y = -120 mph
\n" ); document.write( " y = 20
\n" ); document.write( "Plane speed 100 mph
\n" ); document.write( "wind speed 20 mph
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\n" ); document.write( "m.ananth@hotmail.ca
\n" ); document.write( " \n" ); document.write( "

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