document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=998947>Question 998947</A>: <I><SPAN STYLE=\"word-break: break-all;\"> working together, John and Mark can clean a fish tank in 30 minutes.  If Mark works alone, he can clean it in 50 minutes.  How long does it take John to clean the fish tank alone? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #616632 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52781)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=616632\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "Let &nbsp;j &nbsp;be the number of minutes for John to clean the tank.\r<BR>\n" );
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document.write( "Let &nbsp;m &nbsp;be the number of minutes for Mark to clean the tank.\r<BR>\n" );
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document.write( "Then John will clean &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fj ALIGN=MIDDLE  ALT=\"1%2Fj\"   DISABLED_style= \"max-width:90%; height:auto;\" > &nbsp;part of the tank volume per minute.\r<BR>\n" );
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document.write( "Correspondingly, &nbsp;Mark will clean &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fm ALIGN=MIDDLE  ALT=\"1%2Fm\"   DISABLED_style= \"max-width:90%; height:auto;\" > &nbsp;part of the tank volume per minute.\r<BR>\n" );
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document.write( "Working together, &nbsp;John and Mark will clean &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F30 ALIGN=MIDDLE  ALT=\"1%2F30\"   DISABLED_style= \"max-width:90%; height:auto;\" > &nbsp;part of the tank volume per minute. &nbsp;It means that\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fj ALIGN=MIDDLE  ALT=\"1%2Fj\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fm ALIGN=MIDDLE  ALT=\"1%2Fm\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F30 ALIGN=MIDDLE  ALT=\"1%2F30\"   DISABLED_style= \"max-width:90%; height:auto;\" >. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1)\r<BR>\n" );
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document.write( "From the other part of the condition, &nbsp;Mark is cleaning &nbsp;<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F50 ALIGN=MIDDLE  ALT=\"1%2F50\"   DISABLED_style= \"max-width:90%; height:auto;\" > &nbsp;part of the tank volume per minute working alone. &nbsp;It means that\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fm ALIGN=MIDDLE  ALT=\"1%2Fm\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F50 ALIGN=MIDDLE  ALT=\"1%2F50\"   DISABLED_style= \"max-width:90%; height:auto;\" >. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2)\r<BR>\n" );
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document.write( "Substitute &nbsp;(2) &nbsp;into &nbsp;(1). &nbsp;You will get\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fj ALIGN=MIDDLE  ALT=\"1%2Fj\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F50 ALIGN=MIDDLE  ALT=\"1%2F50\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F30 ALIGN=MIDDLE  ALT=\"1%2F30\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "Hence,\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Fj ALIGN=MIDDLE  ALT=\"1%2Fj\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F30 ALIGN=MIDDLE  ALT=\"1%2F30\"   DISABLED_style= \"max-width:90%; height:auto;\" > - <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F50 ALIGN=MIDDLE  ALT=\"1%2F50\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2850-30%29%2F1500 ALIGN=MIDDLE  ALT=\"%2850-30%29%2F1500\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20%2F1500 ALIGN=MIDDLE  ALT=\"20%2F1500\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F150 ALIGN=MIDDLE  ALT=\"2%2F150\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F75 ALIGN=MIDDLE  ALT=\"1%2F75\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "Thus &nbsp;j = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=75%2F1 ALIGN=MIDDLE  ALT=\"75%2F1\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 75 minutes.\r<BR>\n" );
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document.write( "<U>Answer</U>. &nbsp;It will take &nbsp;75 &nbsp;minutes for Mark to clean the tank working alone.\r<BR>\n" );
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