document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=336210>Question 336210</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An auditorium has 20 rows of seats.These are 20 seats in the first row,21 in the second row and 22 in the third row and so on.how many seats are there in all rows?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #241074 by </B><A HREF=/tutors/aboutme.mpl?userid=galactus><B>galactus(183)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=galactus><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=galactus><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=241074\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Did you try just adding them up?. 20+21+22+23+24+....+39\r<BR>\n" );
document.write( "\n" );
document.write( "There is a shortcut, though, using the sum of arithmetic sequences.\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=Sn=n%2F2%2A%28a1%2Ba2%29 ALIGN=MIDDLE  ALT=\"Sn=n%2F2%2A%28a1%2Ba2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a1=20 ALIGN=MIDDLE  ALT=\"a1=20\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=an=39 ALIGN=MIDDLE  ALT=\"an=39\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=d=20 ALIGN=MIDDLE  ALT=\"d=20\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
document.write( "\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=20%2F2%2A%2820%2B39%29=10%2859%29=590 ALIGN=MIDDLE  ALT=\"20%2F2%2A%2820%2B39%29=10%2859%29=590\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );