document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1088710>Question 1088710</A>: <I><SPAN STYLE=\"word-break: break-all;\"> It takes Nicolai one and a half hours to paint the walls of a room and two hours to paint the ceiling. Elena needs exactly one hour to paint the walls of the same room and one hour to paint the ceiling. If Nicolai and Elena work together, what is the shortest possible time in minutes in which they can paint the walls and the ceiling of that room?\r<BR>\n" );
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document.write( "My answer is 76, but the correct answer is apparently 72. Can someone please explain the working? Thank you! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #703023 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=703023\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  It takes Nicolai one and a half hours to paint the walls of a room and two hours to paint the ceiling.<BR>\n" );
document.write( " 3.5 * 60 = 210 min for N to do the job<BR>\n" );
document.write( " Elena needs exactly one hour to paint the walls of the same room and one hour to paint the ceiling.<BR>\n" );
document.write( "2 * 60 = 120 min for E to do the job<BR>\n" );
document.write( " If Nicolai and Elena work together, what is the shortest possible time in minutes in which they can paint the walls and the ceiling of that room?<BR>\n" );
document.write( "let t = time required when working together<BR>\n" );
document.write( "let the completed job = 1<BR>\n" );
document.write( "A shared work equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%2F210 ALIGN=MIDDLE  ALT=\"t%2F210\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%2F120 ALIGN=MIDDLE  ALT=\"t%2F120\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1 <BR>\n" );
document.write( "each will do a fraction of the job, the 2 fractions add up to 1<BR>\n" );
document.write( "multiply the equation by least common denominator, 840<BR>\n" );
document.write( "840*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%2F210 ALIGN=MIDDLE  ALT=\"t%2F210\"   DISABLED_style= \"max-width:90%; height:auto;\" > + 840*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=t%2F120 ALIGN=MIDDLE  ALT=\"t%2F120\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 840<BR>\n" );
document.write( "cancel the denominators<BR>\n" );
document.write( "4t + 7t = 840<BR>\n" );
document.write( "11t = 840<BR>\n" );
document.write( "t = 840/11<BR>\n" );
document.write( "t = 76.4 ~ 76 hrs working together, I think you are right  </SPAN>\n" );
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