document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=679020>Question 679020</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Mark can mow a lawn in 20 minutes less than his sister Marie. Together they can mow the lawn in 24 minutes. How long would it take Marie to finish the mowing if she worked alone? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #421746 by </B><A HREF=/tutors/aboutme.mpl?userid=nerdybill><B>nerdybill(7384)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nerdybill><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=nerdybill><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=421746\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">     Mark can mow a lawn in 20 minutes less than his sister Marie. Together they can mow the lawn in 24 minutes. How long would it take Marie to finish the mowing if she worked alone?<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Let x = time (mins) it takes Marie<BR>\n" );
document.write( "then<BR>\n" );
document.write( "x-20 = time (mins) it takes Mark<BR>\n" );
document.write( ".<BR>\n" );
document.write( "24(1/x + 1/(x-20)) = 1<BR>\n" );
document.write( "multiplying both sides by x(x-20):<BR>\n" );
document.write( "24((x-20) + x) = x(x-20)<BR>\n" );
document.write( "24(2x-20) = x^2-20x<BR>\n" );
document.write( "48x-480 = x^2-20x<BR>\n" );
document.write( "-480 = x^2-68x<BR>\n" );
document.write( "0 = x^2-68x+480<BR>\n" );
document.write( "0 = (x-8)(x-60)<BR>\n" );
document.write( "x = {8,60}<BR>\n" );
document.write( "throw out 8 (extraneous) leaving:<BR>\n" );
document.write( "x = 60 minutes<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );