document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=316581>Question 316581</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A bookstore can purchase several calculators for a total cost of $216. If each calculator cost $2 less, the bookstore could purchase 9 additional calculators at the same total cost. How many calculators, n, can be purchased at the regular price? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #226479 by </B><A HREF=/tutors/aboutme.mpl?userid=texttutoring><B>texttutoring(324)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=texttutoring><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=texttutoring><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=226479\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let n = number of calculators<BR>\n" );
document.write( "Let p = original price of calculators\r<BR>\n" );
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document.write( "You have two variables, so you need two equations:\r<BR>\n" );
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document.write( "Equation 1: 216 = np<BR>\n" );
document.write( "Equation 2: 216 = (n+9)(p-2)\r<BR>\n" );
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document.write( "Isolate for n in Equation 1: n = 216/p\r<BR>\n" );
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document.write( "Now plug this value into Equation 2 and solve for p:\r<BR>\n" );
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document.write( "216 =(216/p + 9)(p-2)\r<BR>\n" );
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document.write( "Do FOIL:\r<BR>\n" );
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document.write( "216 = 216 + 9p -432/p -18<BR>\n" );
document.write( "0 = 9p -432/p -18\r<BR>\n" );
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document.write( "Multiply everything by p:\r<BR>\n" );
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document.write( "0 = 9p^2 -18p -432<BR>\n" );
document.write( "0 = 9(p^2 -2p -48)<BR>\n" );
document.write( "0 = 9(p-8)(p+6)\r<BR>\n" );
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document.write( "So either p=8 or p=-6. We have to choose the positive value, because a negative price wouldn't make sense.\r<BR>\n" );
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document.write( "Now let's solve for n:\r<BR>\n" );
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document.write( "n=216/p<BR>\n" );
document.write( "n=216/8<BR>\n" );
document.write( "n=27\r<BR>\n" );
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document.write( "So 27 calculators can be purchased at the regular price of $8 each. </SPAN>\n" );
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