document.write( "Question 1179659: Flying with the wind, a plane flew 1,120 mi in 4 h. Against the wind, the plane required 7 h to fly the same distance. Find the rate of the plane in calm air and the rate of the wind. \n" ); document.write( "

Algebra.Com's Answer #809226 by mananth(16946) $\"\"$ $\"About$

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Plane speed =x mph in still air
\n" ); document.write( "wind speed =y mph
\n" ); document.write( "against wind x-y 7.00 hours
\n" ); document.write( "with wind x+y 4.00 hours
\n" ); document.write( "
\n" ); document.write( "Distance = same= 1120 miles
\n" ); document.write( "t=d/r
\n" ); document.write( "1120 / ( x - y )= 7.00
\n" ); document.write( "1120.00 /( x + y) = 4.00
\n" ); document.write( "1 x -1 y = 160.00 ....................1
\n" ); document.write( "1120 / ( x+ 1 y )= 4.00
\n" ); document.write( "1120.00 /( x - 1 y) = 4.00
\n" ); document.write( "1.00 x + 1.00 y = 280.00 ...............2
\n" ); document.write( "Multiply (1) by 1.00
\n" ); document.write( "Multiply (2) by 1.00
\n" ); document.write( "we get
\n" ); document.write( "1 x + 1 y = 160
\n" ); document.write( "1 x - 1 y = 280
\n" ); document.write( "2 x = 440
\n" ); document.write( "/ 2
\n" ); document.write( "x = 220 mph
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "1 x -1.00 y = 160.00
\n" ); document.write( "220 -1.00 y = 160.00
\n" ); document.write( "- y = 160 -220
\n" ); document.write( "- y = -60
\n" ); document.write( " y = 60 mph
\n" ); document.write( " \n" ); document.write( "

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