document.write( "Question 1027125: A freight train covered 120 miles at a certain speed. Had the train been able to travel 10 mph faster, the trip would have been 2 hours shorter. How fast did the train go?
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Algebra.Com's Answer #642379 by stanbon(75887) $\"\"$ $\"About$

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A freight train covered 120 miles at a certain speed. Had the train been able to travel 10 mph faster, the trip would have been 2 hours shorter. How fast did the train go?
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\n" ); document.write( "slower DATA:
\n" ); document.write( "dist = 120 miles ; rate = x mph ; time = 120/x hrs
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\n" ); document.write( "faster DATA:
\n" ); document.write( "dist = 120 miles ; rate = x+10 mph ; time = 120/(x+10) hrs
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\n" ); document.write( "Equation:
\n" ); document.write( "longer time - shorter time = 2hr
\n" ); document.write( "120/x - 120/(x+10) = 2 hr
\n" ); document.write( "120x + 120*10 - 120x = 2x(x+10)
\n" ); document.write( "2x^2 + 20x - 120*10 = 0
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\n" ); document.write( "x^2 + 10x - 600 = 0
\n" ); document.write( "x = 20 mph (slower rate)
\n" ); document.write( "x+10 = 30 (faster rate)
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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