document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=180852>Question 180852</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a train normally travels 240km at a certain speed. one day, due to bad weather, the train's speed is reduced by 20km/h so that the journey takes two hours longer. find the normal speed. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #135624 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=135624\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a train normally travels 240km at a certain speed. one day, due to bad weather, the train's speed is reduced by 20km/h so that the journey takes two hours longer. find the normal speed.<BR>\n" );
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document.write( "Normal-travel DATA:<BR>\n" );
document.write( "distance = 240 km ; rate = x km/h ; time = d/r = 240/x hrs<BR>\n" );
document.write( "---------------------<BR>\n" );
document.write( "Bad weather DATA:<BR>\n" );
document.write( "distance = 240 km ; rate = (x-20) km/h ;time = 240/(x-20) hrs<BR>\n" );
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document.write( "Bad time - normal time = 2 hrs<BR>\n" );
document.write( "240/(x-20) - 240/x = 2<BR>\n" );
document.write( "120/(x-20) - 120/x = 1\r<BR>\n" );
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document.write( "120x -120(x-20) = x(x-20)\r<BR>\n" );
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document.write( "20 = x^2 -20x <BR>\n" );
document.write( "x^2 - 20x - 20 = 0\r<BR>\n" );
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document.write( "x = [20 +- sqrt(20^2 - 4*1*-20)]/2\r<BR>\n" );
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document.write( "x = [20 +- sqrt(480)]/2\r<BR>\n" );
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document.write( "x = [20 +- 4sqrt(30)]/2\r<BR>\n" );
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document.write( "x = 10 +- 2sqrt(30)<BR>\n" );
document.write( "===========================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );