document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1060529>Question 1060529</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Ravi bought a desktop computer and a laptop computer. Before finance charges, the laptop cost <BR>\n" );
document.write( "$300<BR>\n" );
document.write( " less than the desktop. He paid for the computers using two different financing plans. For the desktop the interest rate was <BR>\n" );
document.write( "6%<BR>\n" );
document.write( " per year, and for the laptop it was <BR>\n" );
document.write( "7%<BR>\n" );
document.write( " per year. The total finance charges for one year were <BR>\n" );
document.write( "$252<BR>\n" );
document.write( ". How much did each computer cost before finance charges?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #675461 by </B><A HREF=/tutors/aboutme.mpl?userid=math_helper><B>math_helper(2461)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=math_helper><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=math_helper><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=675461\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "Let d = cost of desktop<BR>\n" );
document.write( "and let a = cost of laptop  <BR>\n" );
document.write( "--<BR>\n" );
document.write( "Write down what we know<BR>\n" );
document.write( "   a = d - 300   (1)<BR>\n" );
document.write( "0.06d + 0.07a = 252  (2)    <BR>\n" );
document.write( "—<BR>\n" );
document.write( "Eq (1) allows us to substitute \"d-300\" for \"a\" in (2):<BR>\n" );
document.write( "  0.06d + 0.07(d-300) = 252<BR>\n" );
document.write( "      0.13d - 21 = 252<BR>\n" );
document.write( "         0.13d = 273<BR>\n" );
document.write( "                d = 273/0.13 = 2100\r<BR>\n" );
document.write( "\n" );
document.write( "—<BR>\n" );
document.write( "Ans:<BR>\n" );
document.write( "Desktop cost was $2100<BR>\n" );
document.write( "Laptop cost was therefore $1800<BR>\n" );
document.write( "—\r<BR>\n" );
document.write( "\n" );
document.write( "Check:   2100(0.06) + 1800(0.07) = 126 + 126 = 252  (ok, finance charges add up)<BR>\n" );
document.write( "           \r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );