document.write( "Question 530172: a train travels 180 miles in an hour less time than a bus traveling the same distance. if the speed of the bus is 15 mph slower that the speed of the train, find the speed of the train and bus? \n" ); document.write( "
Algebra.Com's Answer #349927 by ankor@dixie-net.com(22740)\"\" \"About 
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a train travels 180 miles in an hour less time than a bus traveling the same distance.
\n" ); document.write( " if the speed of the bus is 15 mph slower that the speed of the train, find the speed of the train and bus?
\n" ); document.write( ":
\n" ); document.write( "Let s = speed of the bus
\n" ); document.write( "then
\n" ); document.write( "(s+15) = speed of the train
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\n" ); document.write( "Write a time equation, time = dist/speed
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\n" ); document.write( "Bus time - train time = 1 hr
\n" ); document.write( "\"180%2Fs\" - \"180%2F%28s%2B15%29\" = 1
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\n" ); document.write( "multiply by s(s+15); results:
\n" ); document.write( "180(s+15) - 180s = s(s+15)
\n" ); document.write( "180s + 2700 - 180s = s^2 + 15s
\n" ); document.write( ":
\n" ); document.write( "a quadratic equation
\n" ); document.write( "s^2 + 15s - 2700 = 0
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\n" ); document.write( "Factor to
\n" ); document.write( "(s+60)(s-45) = 0
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\n" ); document.write( "the positive solution
\n" ); document.write( "s = 45 mph is the speed of the bus
\n" ); document.write( "then
\n" ); document.write( "45 + 15 = 60 mph is the speed of the train
\n" ); document.write( ":
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\n" ); document.write( "Check this by finding the times of each
\n" ); document.write( "180/45 = 4 hrs
\n" ); document.write( "180/60 = 3 hrs
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\n" ); document.write( "differ: 1 hrs
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