document.write( "Question 614334: The average speed of an express train is 15 mph faster than the average of a local train. It takes the local train 2 hours longer than the express train to cover 360 miles. What is the average speed of the express train? \n" ); document.write( "
Algebra.Com's Answer #386523 by lwsshak3(11628)\"\" \"About 
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The average speed of an express train is 15 mph faster than the average of a local train. It takes the local train 2 hours longer than the express train to cover 360 miles. What is the average speed of the express train?\r
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\n" ); document.write( "let x=speed of the local train
\n" ); document.write( "x+15=speed of express train
\n" ); document.write( "travel time=distance/speed
\n" ); document.write( "..
\n" ); document.write( "360/x-360/(x+15)=2
\n" ); document.write( "360(x+15)-360x=2x(x+15)=2x^2+30x
\n" ); document.write( "360x+5400-360x=2x^2+30x
\n" ); document.write( "2x^2+30x-5400=0
\n" ); document.write( "x^2+15x-2700=0
\n" ); document.write( "(x-45)(x+60)=0
\n" ); document.write( "x=-60(reject, x>0)
\n" ); document.write( "or
\n" ); document.write( "x=45
\n" ); document.write( "x+15=60
\n" ); document.write( "ans:
\n" ); document.write( "speed of express train=60 mph
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