document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=248810>Question 248810</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Sam can mow a lawn in 20 minutes and Robert can mow the same lawn in 30 minutes. If they worked together, how long would it take them to do the work?\r<BR>\n" );
document.write( "\n" );
document.write( "I need the rate of work (R), the time of work (T) , and the work done (W)<BR>\n" );
document.write( "the equation is RT = W. \r<BR>\n" );
document.write( "\n" );
document.write( "It would help if I am provided a detailed explanation </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #181336 by </B><A HREF=/tutors/aboutme.mpl?userid=oberobic><B>oberobic(2304)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=oberobic><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=181336\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The critical insight is that you have to get the equations in terms of accomplishing 1 job.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Sam can do the job in 20 min.  So he can do the whole job at the rate of 1 job in 20 minutes.<BR>\n" );
document.write( "So he does 1/20 of the job per minute.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Rob can do the job in 30 min.  His rate is 1/30 of the job per minute.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Working together how does it take?<BR>\n" );
document.write( ".<BR>\n" );
document.write( "1/20*x + 1/30*x = 1 job done<BR>\n" );
document.write( ", where x = minutes.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Multiply everything by 60 go get rid of the fractions.<BR>\n" );
document.write( "3x + 2x = 60<BR>\n" );
document.write( "5x = 60<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Divide both sides by 12<BR>\n" );
document.write( "x = 12<BR>\n" );
document.write( ".<BR>\n" );
document.write( "So our candidate answer is working together it will take them 12 minutes.<BR>\n" );
document.write( ".<BR>\n" );
document.write( "Let's check.<BR>\n" );
document.write( "In 12 minutes, Sam does 12/20 of the job and Rob does 12/30 of the job.<BR>\n" );
document.write( "12/20 = .6<BR>\n" );
document.write( "12/30 = .4<BR>\n" );
document.write( "Total = 1 job done. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );