document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=874737>Question 874737</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A and B can do a piece of work in 72  days. B and C can do it in 120 days. A and C can do it in 90 days. In what time can A alone do it? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #527674 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=527674\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A + B = 72<BR>\n" );
document.write( "B + C = 120<BR>\n" );
document.write( "A + C = 90<BR>\n" );
document.write( "therefore<BR>\n" );
document.write( "B = 120 - C<BR>\n" );
document.write( "C = 90 - A<BR>\n" );
document.write( "B = 120 - 90 + A = 30 + A<BR>\n" );
document.write( "A + 30 + A = 72<BR>\n" );
document.write( "2A = 42<BR>\n" );
document.write( "A = 21 days<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );