document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=405938>Question 405938</A>: <I><SPAN STYLE=\"word-break: break-all;\">  Ben invested $800, part at 9% per annum and the rest at 12% per annum. After one year the total interest earned was $79.50. How much did he invest?\r<BR>\n" );
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document.write( "we are solving them by elimination (gr 11)<BR>\n" );
document.write( "i dont know how to do this one at all. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #286606 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=286606\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  Ben invested $800, part at 9% per annum and the rest at 12% per annum. After one year the total interest earned was $79.50. How much did he invest?\r<BR>\n" );
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document.write( "9% per annum ------  x<BR>\n" );
document.write( "12% per annum--------y\r<BR>\n" );
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document.write( "x+y =800....1\r<BR>\n" );
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document.write( "0.09x+0.12y=$79.50. <BR>\n" );
document.write( "multiply by 100<BR>\n" );
document.write( "9x+12y=7950............(2)\r<BR>\n" );
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document.write( "multiply (1)--9<BR>\n" );
document.write( "-9x-9y=-7200<BR>\n" );
document.write( "add to (2)<BR>\n" );
document.write( "+3y=750<BR>\n" );
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document.write( "y = $250 ===> at 12%<BR>\n" );
document.write( "Balance $550 ay 9%<BR>\n" );
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