document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=127989>Question 127989</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 2)  Pipe A can fill a tank in 4hr. Pipe B can fill the tank in 9hr less than the time it takes pipe C, a drain pipe, to empty the tank. When all three pipes are open, it takes 2hr to fill the tank. How much time is required for pipe C to empty the tank if pipes 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 #93738 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=93738\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  Pipe A can fill a tank in 4 hr. Pipe B can fill the tank in 9 hr less than the time it takes pipe C, a drain pipe, to empty the tank. When all three pipes are open, it takes 2 hr to fill the tank. How much time is required for pipe C to empty the tank if pipes A and B are closed?<BR>\n" );
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document.write( "Pipe C's draining time = x (when Pipes A & B are closed)<BR>\n" );
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document.write( "Pipes A's filling time = 4 hr (given)<BR>\n" );
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document.write( "Pipe B's filling time = (x-9) (Given as 9 hrs less than C)<BR>\n" );
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document.write( "Let the full tank = 1<BR>\n" );
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document.write( "Filling is +, draining is -<BR>\n" );
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document.write( "The equation when all three are open for 2 hrs:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F4 ALIGN=MIDDLE  ALT=\"2%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F%28%28x-9%29%29 ALIGN=MIDDLE  ALT=\"2%2F%28%28x-9%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2Fx ALIGN=MIDDLE  ALT=\"2%2Fx\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
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document.write( "Multiply the equation by 4x(x-9) to get rid of the denominators:<BR>\n" );
document.write( "4x(x-9)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F4 ALIGN=MIDDLE  ALT=\"2%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" > + 4x(x-9)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F%28%28x-9%29%29 ALIGN=MIDDLE  ALT=\"2%2F%28%28x-9%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > - 4x(x-9)*<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2Fx ALIGN=MIDDLE  ALT=\"2%2Fx\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 4x(x-9)(1)<BR>\n" );
document.write( "Cancel out the denominators and you have:\r<BR>\n" );
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document.write( "x(x-9)*2 + 4x(2) - 4(x-9)*2 = 4x(x-9)<BR>\n" );
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document.write( "2x^2 - 18x + 8x - 8x + 72 = 4x^2 - 36x<BR>\n" );
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document.write( "2x^2 - 4x^2 - 18x + 36x + 72 = 0<BR>\n" );
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document.write( "-2x^2 - 18x + 72 = 0<BR>\n" );
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document.write( "x^2 - 9x - 36 = 0; Divide by -2; simplifies and changes the signs<BR>\n" );
document.write( "Factors to<BR>\n" );
document.write( "(x + 3) (x - 12) = 0<BR>\n" );
document.write( "Positive solution<BR>\n" );
document.write( "x = 12 hrs for the the drain to empty the tank with A & B closed<BR>\n" );
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document.write( "Check solution (B's fill time will be 12-9 = 3 hrs)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F4 ALIGN=MIDDLE  ALT=\"2%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F3 ALIGN=MIDDLE  ALT=\"2%2F3\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F12 ALIGN=MIDDLE  ALT=\"2%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" > =<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=6%2F12 ALIGN=MIDDLE  ALT=\"6%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=8%2F12 ALIGN=MIDDLE  ALT=\"8%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F12 ALIGN=MIDDLE  ALT=\"2%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" > =  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=12%2F12 ALIGN=MIDDLE  ALT=\"12%2F12\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 1<BR>\n" );
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