document.write( "Question 380432: A plane traveled a distance of 800 miles and returned the same distance. If the rate returning is 40 miles per hour faster than the rate going, and if the total flight took 8 hours, how fast did the plane travel on the return trip? \n" ); document.write( "
Algebra.Com's Answer #269988 by stanbon(75887)\"\" \"About 
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A plane traveled a distance of 800 miles and returned the same distance. If the rate returning is 40 miles per hour faster than the rate going, and if the total flight took 8 hours, how fast did the plane travel on the return trip?
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\n" ); document.write( "Going DATA:
\n" ); document.write( "distance = 800 miles ; rate = x mph ; time = 800/x hrs
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\n" ); document.write( "Return DATA:
\n" ); document.write( "distance = 800 miles ; rate = (x+40) mph ; time = 800/(x+40) hrs
\n" ); document.write( "---------------------
\n" ); document.write( "Equation:
\n" ); document.write( "time + time = 8 hrs.
\n" ); document.write( "800/x + 800/(x+40) = 8
\n" ); document.write( "800(x+40) + 800x = 8x(x+40)
\n" ); document.write( "1600x + 32000 = 8x^2+320x
\n" ); document.write( "8x^2- 1280x -32000 = 0
\n" ); document.write( "x^2 - 160x - 4000 = 0
\n" ); document.write( "Positive solution:
\n" ); document.write( "x = 181.98 mph
\n" ); document.write( "x+40 = 221.98 mph (return leg speed)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
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