document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1192357>Question 1192357</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A water tank can be filled in 9 hours and then drained in 12 hours. How long would it take to fill the water tank if the drain is left open? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #824257 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13200)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=824257\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "The other tutor showed a standard algebraic method for solving this kind of \"working together\" problem.<br><BR>\n" );
document.write( "Here is an alternative you might try that many students like because it avoids solving equations with fractions.<br><BR>\n" );
document.write( "Consider the least common multiple of the two given times, which is 36 hours.<br><BR>\n" );
document.write( "In 36 hours, the number of tanks that could be filled is 36/9 = 4; in 36 hours the number of tanks that could be drained is 36/12 = 3.  So in 36 hours the net would be filling the tank 4-3 = 1 time.<br><BR>\n" );
document.write( "ANSWER: 36 hours<br><BR>\n" );
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