document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=468221>Question 468221</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Twin brothers, Billy and Bobby, can mow their grandparent's lawn together in 69 minutes. Billy could mow the lawn by himself in 15 minutes less time that it would take Bobby. How long would it take Bobby to mow the lawn by himself? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #321267 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=321267\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Bobby takes x hours<BR>\n" );
document.write( "so he does 1/x of the job in 1 minute\r<BR>\n" );
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document.write( "Billy mows in x-15 minutes<BR>\n" );
document.write( "so he does 1/(x-15)of the job in 1 minute\r<BR>\n" );
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document.write( "together they do in 69 minutes<BR>\n" );
document.write( "so they do 1/69 of the job in 1 minute\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fx+%2B+1%2F%28x-15%29+=+1%2F69 ALIGN=MIDDLE  ALT=\"1%2Fx+%2B+1%2F%28x-15%29+=+1%2F69\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "LCD = 69x(x-1)<BR>\n" );
document.write( "Multiply the equation by the LCD\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=69%28x-1%29%2B+69x=+x%28x-1%29 ALIGN=MIDDLE  ALT=\"69%28x-1%29%2B+69x=+x%28x-1%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "69x-69+69x=x^2-x\r<BR>\n" );
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document.write( "x^2-x-138x=-69\r<BR>\n" );
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document.write( "x^2-139x+69=0\r<BR>\n" );
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document.write( "Find the roots of the equation by quadratic formula							<BR>\n" );
document.write( "							<BR>\n" );
document.write( "a=	1	,b=	-139	,c=	69		<BR>\n" );
document.write( "							<BR>\n" );
document.write( "b^2-4ac=	19321	-276				<BR>\n" );
document.write( "b^2-4ac=	19045						<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( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x1=%28-12%2Bsqrt%2824%29%29%2F%2812%29 ALIGN=MIDDLE  ALT=\"x1=%28-12%2Bsqrt%2824%29%29%2F%2812%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >							<BR>\n" );
document.write( "x1=(	139	+	138	)/	2		<BR>\n" );
document.write( "x1=	138.5						<BR>\n" );
document.write( "x2=(	139	-138	) /	2			<BR>\n" );
document.write( "x2= 	0.5		\r<BR>\n" );
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document.write( "Bobby takes 138.5 minutes<BR>\n" );
document.write( "Billy takes 125.5 minutes				<BR>\n" );
document.write( " </SPAN>\n" );
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