document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=607135>Question 607135</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Pipe A can fill a tank in 4 h.  Pipe B can fill the tank in 9 h less than the time it takes pipe C, a drain pipe, to empty the tank.  When all 3 pipes are open, it takes 2 h to fill the tank.  How much time is required for pipe C to empty the tank if pipe A and B are closed. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #382434 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=382434\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Add the rates of filling and subtract the<BR>\n" );
document.write( "rate of emptying<BR>\n" );
document.write( "A's rate: ( 1 tank filled ) / ( 4 hrs )<BR>\n" );
document.write( "B's rate: ( 1 tank filled ) / ( C's rate minus 9 hrs )<BR>\n" );
document.write( "C's rate: ( 1 tank emptied ) / ( x hrs )<BR>\n" );
document.write( "--------<BR>\n" );
document.write( "When all 3 pipes are open, it takes 2 hrs to fill the tank.<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+1%2F4+%2B+1%2F%28+x-9+%29+-+1%2Fx+=+1%2F2+ ALIGN=MIDDLE  ALT=\"+1%2F4+%2B+1%2F%28+x-9+%29+-+1%2Fx+=+1%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Multiply both sides by <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+4%2Ax%2A%28+x-9+%29+ ALIGN=MIDDLE  ALT=\"+4%2Ax%2A%28+x-9+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%2A%28+x-9+%29+%2B+4c+-+4%2A%28+x-9+%29+=+2%2Ax%2A%28+x-9+%29+ ALIGN=MIDDLE  ALT=\"+x%2A%28+x-9+%29+%2B+4c+-+4%2A%28+x-9+%29+=+2%2Ax%2A%28+x-9+%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+9x+%2B+4x+-+4x+%2B+36+=+2x%5E2+-+18x+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+9x+%2B+4x+-+4x+%2B+36+=+2x%5E2+-+18x+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+9x+=+2x%5E2+-+18x+-+36+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+9x+=+2x%5E2+-+18x+-+36+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x%5E2+-+9x+-+36+=+0+ ALIGN=MIDDLE  ALT=\"+x%5E2+-+9x+-+36+=+0+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Use quadratic formula<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"+x+=+%28-b+%2B-+sqrt%28+b%5E2+-+4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+a+=+1+ ALIGN=MIDDLE  ALT=\"+a+=+1+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+b+=+-9+ ALIGN=MIDDLE  ALT=\"+b+=+-9+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+c+=+-36+ ALIGN=MIDDLE  ALT=\"+c+=+-36+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+%28-%28-9%29+%2B-+sqrt%28+%28-9%29%5E2+-+4%2A1%2A%28-36%29+%29%29+%2F+%282%2A1%29+ ALIGN=MIDDLE  ALT=\"+x+=+%28-%28-9%29+%2B-+sqrt%28+%28-9%29%5E2+-+4%2A1%2A%28-36%29+%29%29+%2F+%282%2A1%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+%28+9+%2B-+sqrt%28+81+%2B+144+%29%29+%2F+2+ ALIGN=MIDDLE  ALT=\"+x+=+%28+9+%2B-+sqrt%28+81+%2B+144+%29%29+%2F+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+%28+9+%2B-+sqrt%28+225+%29%29+%2F+2+ ALIGN=MIDDLE  ALT=\"+x+=+%28+9+%2B-+sqrt%28+225+%29%29+%2F+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+%28+9+%2B+15%29+%2F+2+ ALIGN=MIDDLE  ALT=\"+x+=+%28+9+%2B+15%29+%2F+2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+24%2F2+ ALIGN=MIDDLE  ALT=\"+x+=+24%2F2+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+x+=+12+ ALIGN=MIDDLE  ALT=\"+x+=+12+\"   DISABLED_style= \"max-width:90%; height:auto;\" > ( ignore the negative square root )<BR>\n" );
document.write( "--------------<BR>\n" );
document.write( "If A and B are closed, C can empty the tank in 12 hrs\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );