document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=324943>Question 324943</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The average age of all the students of a class is 18.0 years. The average age of boys of the class is 20 years and that of the girls is 15 years. If the number of girls in the class is 20, then find the number of boys in the class? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #232704 by </B><A HREF=/tutors/aboutme.mpl?userid=Fombitz><B>Fombitz(32388)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Fombitz><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=Fombitz><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=232704\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let B be the sum of the boys' ages, G the sum of the girls' ages.<BR>\n" );
document.write( "Let Ng be the number of girls, Nb the number of boys.<BR>\n" );
document.write( ".<BR>\n" );
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document.write( "1.<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28B%2BG%29%2F%28Ng%2BNb%29=18 ALIGN=MIDDLE  ALT=\"%28B%2BG%29%2F%28Ng%2BNb%29=18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "2.<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=B%2FNb=20 ALIGN=MIDDLE  ALT=\"B%2FNb=20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "3.<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=G%2FNg=15 ALIGN=MIDDLE  ALT=\"G%2FNg=15\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "4.<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=Ng=20 ALIGN=MIDDLE  ALT=\"Ng=20\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "From eq. 3 and 4, <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=G=300 ALIGN=MIDDLE  ALT=\"G=300\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "From eq. 2, <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=B=20Nb ALIGN=MIDDLE  ALT=\"B=20Nb\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Substitute into eq. 1,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%2820Nb%2B300%29%2F%2820%2BNb%29=18 ALIGN=MIDDLE  ALT=\"%2820Nb%2B300%29%2F%2820%2BNb%29=18\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20Nb%2B300=18%2820%2BNb%29 ALIGN=MIDDLE  ALT=\"20Nb%2B300=18%2820%2BNb%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20Nb%2B300=360%2B18Nb ALIGN=MIDDLE  ALT=\"20Nb%2B300=360%2B18Nb\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2Nb=60 ALIGN=MIDDLE  ALT=\"2Nb=60\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28Nb=30%29 ALIGN=MIDDLE  ALT=\"highlight%28Nb=30%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );