document.write( "Question 112477: Flying with the wind a plane flew 1800 mi. in 3 hours. Against the wind, the plane required 5 hours to fly the same distance. Find the rate of the plane in calm air. \n" ); document.write( "
Algebra.Com's Answer #82063 by ptaylor(2198)\"\" \"About 
You can put this solution on YOUR website!
Distance(d)=Rate(r) times Time(t) or d=rt; r=d/t and t=d/r\r
\n" ); document.write( "\n" ); document.write( "Let r=rate (speed) of plane in calm air
\n" ); document.write( "And let w=rate (speed) of the wind\r
\n" ); document.write( "\n" ); document.write( "Going with the wind:\r
\n" ); document.write( "\n" ); document.write( "r+w=1800/3=600 mph--------------------------eq1\r
\n" ); document.write( "\n" ); document.write( "Going against the wind:\r
\n" ); document.write( "\n" ); document.write( "r-w=1800/5=360 mph-----------------------------------eq2\r
\n" ); document.write( "\n" ); document.write( "Add eq1 and eq2:\r
\n" ); document.write( "\n" ); document.write( "2r=960 divide both sides by 2
\n" ); document.write( "r=480 mph--------------------------------rate (speed) of plane in calm air\r
\n" ); document.write( "\n" ); document.write( "Substituting into eq1:\r
\n" ); document.write( "\n" ); document.write( "480+w=600 subtract 480 from both sides\r
\n" ); document.write( "\n" ); document.write( "w=120 mph---------------- speed of wind\r
\n" ); document.write( "\n" ); document.write( "CK\r
\n" ); document.write( "\n" ); document.write( "(480+120)*3=1800
\n" ); document.write( "1800=1800
\n" ); document.write( "(480-120)*5=1800
\n" ); document.write( "360*5=1800
\n" ); document.write( "1800=1800\r
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\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor\r
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