document.write( "Question 422162: against the wind a small plane flew 21 miles in 1 hr and 10 minutes, the return trip only took 50 minutes. what was the speed of the wind, what was the speed of the plane in still air \n" ); document.write( "

Algebra.Com's Answer #294709 by mananth(16946) $\"\"$ $\"About$

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against wind 1 1/6 hours
\n" ); document.write( "with wind 5/6 hours
\n" ); document.write( "
\n" ); document.write( "Distance = same= 21 miles
\n" ); document.write( "plane speed =x
\n" ); document.write( "wind speed =y
\n" ); document.write( "t=d/r
\n" ); document.write( "21/(x-y)=1.17
\n" ); document.write( "1.17(x-y)=21.00
\n" ); document.write( "1.17x-1.17y=21 ....................1
\n" ); document.write( "21/(x+y)= 5/6
\n" ); document.write( " 5/6(x+y )=21
\n" ); document.write( " 5/6x+ 5/6y=21 ...............2
\n" ); document.write( "Multiply (1) by 5
\n" ); document.write( "Multiply (2) by 8
\n" ); document.write( "we get
\n" ); document.write( "5.83x-5.83y=105
\n" ); document.write( "6.67x+6.67y=168
\n" ); document.write( "12.5x=273
\n" ); document.write( "/12.5
\n" ); document.write( "x=21.84 mph plane speed
\n" ); document.write( "
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "1.17x-1.17y=21
\n" ); document.write( "25.48-1.17y=21
\n" ); document.write( "-1.17y=21-25.48
\n" ); document.write( "-1.17y=-4.48
\n" ); document.write( "y=3.84 mph wind speed
\n" ); document.write( " \n" ); document.write( "

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