document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=428131>Question 428131</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 3x+4y=15<BR>\n" );
document.write( "-4x-3y=-20\r<BR>\n" );
document.write( "\n" );
document.write( "I need to solve this through the addition method.  Is there an easy way to do this? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #297645 by </B><A HREF=/tutors/aboutme.mpl?userid=htmentor><B>htmentor(1343)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=htmentor><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=htmentor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=297645\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If, by addition method you mean adding one equation to the other, then proceed as follows:<BR>\n" );
document.write( " 3x + 4y =  15 (1)<BR>\n" );
document.write( "-4x - 3y = -20 (2)<BR>\n" );
document.write( "First multiply equation (1) by 4 and equation (2) by 3:<BR>\n" );
document.write( "12x + 16y =  60<BR>\n" );
document.write( "-12x - 9y = -60<BR>\n" );
document.write( "Add the two equations:<BR>\n" );
document.write( "7y = 0 -> y = 0<BR>\n" );
document.write( "Substituting into equation (1) above, we get:<BR>\n" );
document.write( "3x = 15 -> x = 5<BR>\n" );
document.write( "So the solution is x = 5, y = 0<BR>\n" );
document.write( "Below are the graphs of the two functions:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28300%2C200%2C-10%2C10%2C-10%2C10%2C15%2F4-3%2F4%2Ax%2C20%2F3-4%2F3%2Ax%29 ALIGN=MIDDLE  ALT=\"graph%28300%2C200%2C-10%2C10%2C-10%2C10%2C15%2F4-3%2F4%2Ax%2C20%2F3-4%2F3%2Ax%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );