document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1043579>Question 1043579</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If something was purchased at $X, and sold for $28, making X% profit, what was the cost of that something? <BR>\n" );
document.write( "Not certain, but does it have something to do with X^2? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #658718 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=658718\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> the cost was x dollars.<BR>\n" );
document.write( "the item was sold for 28 dollars.<BR>\n" );
document.write( "the profit was x%.\r<BR>\n" );
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document.write( "profit = revenue minus cost.\r<BR>\n" );
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document.write( "therefore profit = 28 - x.\r<BR>\n" );
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document.write( "this profit equals x % of the cost.\r<BR>\n" );
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document.write( "x % of the cost is equal to x / 100 * the cost.\r<BR>\n" );
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document.write( "since the cost is x, then x % of x is equal to x / 100 * x which is equal to x^2 / 100.\r<BR>\n" );
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document.write( "this means that the profit is equal to x^2 / 100.\r<BR>\n" );
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document.write( "since the profit is also equal to 28 - x, you get:\r<BR>\n" );
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document.write( "x^2 / 100 = 28 - x\r<BR>\n" );
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document.write( "multiply both sides of this equation by 100 to get:\r<BR>\n" );
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document.write( "x^2 = 2800 - 100 * x\r<BR>\n" );
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document.write( "add 100 * x and subtract 2800 from both sides of this equation to get:\r<BR>\n" );
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document.write( "x^2 + 100 * x - 2800 = 0\r<BR>\n" );
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document.write( "use the quadratic formula to solve for x.\r<BR>\n" );
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document.write( "you get:\r<BR>\n" );
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document.write( "x = -122.80109889 or x = 22.80109889\r<BR>\n" );
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document.write( "since x represents the cost, and since the cost can't be negative, you are left with:\r<BR>\n" );
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document.write( "x = 22.80109889\r<BR>\n" );
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document.write( "that's your cost.\r<BR>\n" );
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document.write( "x % would be equal to 22.80109889 %\r<BR>\n" );
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document.write( "profit = revenue - cost.\r<BR>\n" );
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document.write( "profit = 28 - 22.80109889 = 5.198901107\r<BR>\n" );
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document.write( "percent profit = 5.198901107 / 22.80109889 = .2280109889 * 100 = 22.80109889 %.\r<BR>\n" );
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document.write( "your solution is that x = 22.80109889 and x % = 22.80109889 %.\r<BR>\n" );
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document.write( "you are correct.\r<BR>\n" );
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document.write( "the solution does have something to do with x^2.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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