document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=816178>Question 816178</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Time taken by a train to travel a distance of 225 km was reduced by 20 minutes when the\r<BR>\n" );
document.write( "\n" );
document.write( "average speed was increased by 20 km/hr. Find its original speed correct to the nearest integer. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #491417 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=491417\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Original - modified time = 20 minutes\r<BR>\n" );
document.write( "\n" );
document.write( "d=225<BR>\n" );
document.write( "speed =x<BR>\n" );
document.write( "modified speed = x+20\r<BR>\n" );
document.write( "\n" );
document.write( "t=d/r\r<BR>\n" );
document.write( "\n" );
document.write( "225/x-225/(x+20) = 1/3 \r<BR>\n" );
document.write( "\n" );
document.write( "multiply by x(x+20)\r<BR>\n" );
document.write( "\n" );
document.write( "225(x+20)-225x=x(x+20)/3\r<BR>\n" );
document.write( "\n" );
document.write( "225x+4500-225x=(x^2+20x)/3<BR>\n" );
document.write( "4500*3= x^2+20x\r<BR>\n" );
document.write( "\n" );
document.write( "x^2+20x-13500 =0\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "solve by quadratic formula<BR>\n" );
document.write( "a=	1	,	b=	20	,	c=	-13500<BR>\n" );
document.write( "							<BR>\n" );
document.write( "b^2-4ac=	400	+	54000				<BR>\n" );
document.write( "b^2-4ac=	54400						<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%09sqrt%28%0954400%09%29=%09233.24%09 ALIGN=MIDDLE  ALT=\"%09sqrt%28%0954400%09%29=%09233.24%09\"   DISABLED_style= \"max-width:90%; height:auto;\" >		<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >							<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x1=%28-b%2Bsqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >							<BR>\n" );
document.write( "x1=(	-20	+	233.24	)/	2		<BR>\n" );
document.write( "x1=	106.62						<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x2=%28-b-sqrt%28b%5E2-4ac%29%29%2F%282a%29 ALIGN=MIDDLE  ALT=\"x2=%28-b-sqrt%28b%5E2-4ac%29%29%2F%282a%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >							<BR>\n" );
document.write( "x2=(	-20	-233.24	) /	2			<BR>\n" );
document.write( "x2=	-126.62						<BR>\n" );
document.write( "Ignore negative value							<BR>\n" );
document.write( "	speed	106.62	mph				\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );