document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=230768>Question 230768</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Using inverse matrix, solve the following problem: \r<BR>\n" );
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document.write( "A high school math department purchased brand A calculators<BR>\n" );
document.write( "for $80 each and brand B calculators for $95 each. It purchased<BR>\n" );
document.write( "a total of 20 calculators at a total cost of $1780. How many brand A<BR>\n" );
document.write( "and brand B calculators did the department purchase?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #170972 by </B><A HREF=/tutors/aboutme.mpl?userid=rfer><B>rfer(16322)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rfer><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=170972\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a+b=20, a=20-b<BR>\n" );
document.write( "80a+95b=1780<BR>\n" );
document.write( "substitute<BR>\n" );
document.write( "80(20-b)+95b=1780<BR>\n" );
document.write( "1600-80b+95b=1780<BR>\n" );
document.write( "15b=180<BR>\n" );
document.write( "b=12=$1140<BR>\n" );
document.write( "a=8=$640 </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );