document.write( "Question 421770: a certain aircraft can fly 1600 miles with the wind in 5 hours and travel the same distance against the wind in 8 hours. What is the spee=d of the wind and the speed of the plane in still air? ( set two equations up ex. y=2x+3 and x=2y+10 and solve using substitution method or addition method) \n" ); document.write( "

Algebra.Com's Answer #294457 by mananth(16946) $\"\"$ $\"About$

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against wind 8 hours
\n" ); document.write( "with wind 5 hours
\n" ); document.write( "
\n" ); document.write( "Distance = same= 1600
\n" ); document.write( "plane speed =x
\n" ); document.write( "wind speed =y
\n" ); document.write( "t=d/r
\n" ); document.write( "1600/(x-y)=8.00
\n" ); document.write( "8(x-y)= 1,600.00
\n" ); document.write( "8x-8y=1600 ....................1
\n" ); document.write( "1600/ ( x + y )= 5
\n" ); document.write( "5 ( x + y ) = 1600
\n" ); document.write( "5 x + 5 y = 1600 ...............2
\n" ); document.write( "Multiply (1) by 5
\n" ); document.write( "Multiply (2) by 8
\n" ); document.write( "we get
\n" ); document.write( "40 x + -40 y = 8000
\n" ); document.write( "40 x + 40 y = 12800
\n" ); document.write( "80 x = 20800
\n" ); document.write( "/80
\n" ); document.write( "x=260 mph plane speed
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "8x-8y=1600
\n" ); document.write( "2080-8y= 1600
\n" ); document.write( "-8y=1600 -2080
\n" ); document.write( "-8y=-480
\n" ); document.write( "y=60mph wind speed
\n" ); document.write( " \n" ); document.write( "

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