document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=885611>Question 885611</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Lala and Baba can finish stacking 200 cups together in 12/5 hrs. One day, Baba stacked by herself. An hour later, Lala joined and they finished the job in 9/5 hrs. If Lala works alone and stacks all 200 cups, how many hours would it take her?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #535303 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=535303\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = Baba's rate of stacking in cups/hr<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BL%5D+ ALIGN=MIDDLE  ALT=\"+R%5BL%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > = Lala's rate of stacking in cups/hr<BR>\n" );
document.write( "Let <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+200+ ALIGN=MIDDLE  ALT=\"+200+\"   DISABLED_style= \"max-width:90%; height:auto;\" > cups stacked = 1 job<BR>\n" );
document.write( "-----------------------<BR>\n" );
document.write( "Add their rates of stacking to get rate stacking together<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+%2B+R%5BL%5D+=+1+%2F+%28+12%2F5+%29+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+%2B+R%5BL%5D+=+1+%2F+%28+12%2F5+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+%2B+R%5BL%5D+=+5%2F12+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+%2B+R%5BL%5D+=+5%2F12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12R%5BB%5D+%2B+12R%5BL%5D+=+5+ ALIGN=MIDDLE  ALT=\"+12R%5BB%5D+%2B+12R%5BL%5D+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------------------<BR>\n" );
document.write( "In 1 hr, Baba stacked:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+%2A+1+=+R%5BB%5D+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+%2A+1+=+R%5BB%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" > cups<BR>\n" );
document.write( "The fraction of the job left to do is:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1+-+R%5BB%5D+ ALIGN=MIDDLE  ALT=\"+1+-+R%5BB%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+%2B+R%5BL%5D+=+%28+1+-+R%5BB%5D+%29+%2F+%28+9%2F5+%29+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+%2B+R%5BL%5D+=+%28+1+-+R%5BB%5D+%29+%2F+%28+9%2F5+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "--------------------------------------<BR>\n" );
document.write( "Multiply both sides of (2) by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9%2F5+ ALIGN=MIDDLE  ALT=\"+9%2F5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+%28+9%2F5+%29%2A%28+R%5BB%5D+%2B+R%5BL%5D+%29+=+1+-+R%5BB%5D+ ALIGN=MIDDLE  ALT=\"+%28+9%2F5+%29%2A%28+R%5BB%5D+%2B+R%5BL%5D+%29+=+1+-+R%5BB%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9%2A%28+R%5BB%5D+%2B+R%5BL%5D+%29+=+5%2A%28+1+-+R%5BB%5D+%29+ ALIGN=MIDDLE  ALT=\"+9%2A%28+R%5BB%5D+%2B+R%5BL%5D+%29+=+5%2A%28+1+-+R%5BB%5D+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+9R%5BB%5D+%2B+9R%5BL%5D+%29+=+5+-+5R%5BB%5D+%29+ ALIGN=MIDDLE  ALT=\"+9R%5BB%5D+%2B+9R%5BL%5D+%29+=+5+-+5R%5BB%5D+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+14R%5BB%5D+%2B+9R%5BL%5D+=+5+ ALIGN=MIDDLE  ALT=\"+14R%5BB%5D+%2B+9R%5BL%5D+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "------------------------<BR>\n" );
document.write( "I can say:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+12R%5BB%5D+%2B+12R%5BL%5D+=+14R%5BB%5D+%2B+9R%5BL%5D+ ALIGN=MIDDLE  ALT=\"+12R%5BB%5D+%2B+12R%5BL%5D+=+14R%5BB%5D+%2B+9R%5BL%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3+R%5BL%5D+=+2R%5BB%5D+ ALIGN=MIDDLE  ALT=\"+3+R%5BL%5D+=+2R%5BB%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BL%5D+=+%282%2F3%29%2AR%5BB%5D+ ALIGN=MIDDLE  ALT=\"+R%5BL%5D+=+%282%2F3%29%2AR%5BB%5D+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "------------------------<BR>\n" );
document.write( "Substitute (1) into (2)<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+14R%5BB%5D+%2B+9R%5BL%5D+=+5+ ALIGN=MIDDLE  ALT=\"+14R%5BB%5D+%2B+9R%5BL%5D+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+14R%5BB%5D+%2B+%282%2F3%29%2A9R%5BB%5D+=+5+ ALIGN=MIDDLE  ALT=\"+14R%5BB%5D+%2B+%282%2F3%29%2A9R%5BB%5D+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+14R%5BB%5D+%2B+6R%5BB%5D+=+5+ ALIGN=MIDDLE  ALT=\"+14R%5BB%5D+%2B+6R%5BB%5D+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+20R%5BB%5D+=+5+ ALIGN=MIDDLE  ALT=\"+20R%5BB%5D+=+5+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+=+1%2F4+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+=+1%2F4+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "and<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BL%5D+=+%282%2F3%29%2A%28+1%2F4+%29+ ALIGN=MIDDLE  ALT=\"+R%5BL%5D+=+%282%2F3%29%2A%28+1%2F4+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BL%5D+=+1%2F6+ ALIGN=MIDDLE  ALT=\"+R%5BL%5D+=+1%2F6+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Working alone, it takes Lala 6 hrs <BR>\n" );
document.write( "-----------------------<BR>\n" );
document.write( "check:<BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+%2B+R%5BL%5D+=+5%2F12+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+%2B+R%5BL%5D+=+5%2F12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1%2F4+%2B+1%2F6+=+5%2F12+ ALIGN=MIDDLE  ALT=\"+1%2F4+%2B+1%2F6+=+5%2F12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(1) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+3%2F12+%2B+2%2F12++=+5%2F12+ ALIGN=MIDDLE  ALT=\"+3%2F12+%2B+2%2F12++=+5%2F12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK<BR>\n" );
document.write( "also:<BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+R%5BB%5D+%2B+R%5BL%5D+=+%28+1+-+R%5BB%5D+%29+%2F+%28+9%2F5+%29+ ALIGN=MIDDLE  ALT=\"+R%5BB%5D+%2B+R%5BL%5D+=+%28+1+-+R%5BB%5D+%29+%2F+%28+9%2F5+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1%2F4+%2B+1%2F6+=+%28+1+-+1%2F4+%29+%2F+%28+9%2F5+%29+ ALIGN=MIDDLE  ALT=\"+1%2F4+%2B+1%2F6+=+%28+1+-+1%2F4+%29+%2F+%28+9%2F5+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5%2F12+=+%28+3%2F4+%29%2A%28+5%2F9+%29+ ALIGN=MIDDLE  ALT=\"+5%2F12+=+%28+3%2F4+%29%2A%28+5%2F9+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "(2) <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+5%2F12+=+5%2F12+ ALIGN=MIDDLE  ALT=\"+5%2F12+=+5%2F12+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "OK\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );