document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=544480>Question 544480</A>: <I><SPAN STYLE=\"word-break: break-all;\"> On a journey of 300km, the train driver calculates that if he reduces his average speed by 10km/h he would take 25 mins longer. Find his average speed </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #355120 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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/cgi-bin/show-face.mpl?user=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=355120\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Original speed	x			<BR>\n" );
document.write( "Changed speed	x	-	10	<BR>\n" );
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document.write( "Distance = same		300	miles	<BR>\n" );
document.write( "original time – time with decreased speed =0.42<BR>\n" );
document.write( "t=d/t				\r<BR>\n" );
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document.write( "300/(x-10)-300/x= 5/12\r<BR>\n" );
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document.write( "300x-300(x-10)= 5*x(x-10)/12\r<BR>\n" );
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document.write( "300x-300x+3000=(5x^2-50x)/12\r<BR>\n" );
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document.write( "multiply by 12\r<BR>\n" );
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document.write( "36000=5x^2-50x<BR>\n" );
document.write( "5x^2-50x-36000=0<BR>\n" );
document.write( "/5<BR>\n" );
document.write( "x*2-10x-7200=0\r<BR>\n" );
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document.write( "x^2-90x+80x-7200=0<BR>\n" );
document.write( "x(x-90)+80(x-90)=0<BR>\n" );
document.write( "(x-90)(x+80=0<BR>\n" );
document.write( "x= 90 mph the average speed. </SPAN>\n" );
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