document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=249495>Question 249495</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a.	Suppose that a market research company finds that at a price of p = $20, they would sell x = 42 tiles each month. If they lower the price to p = $10, then more people would purchase the tile, and they can expect to sell x = 52 tiles in a month’s time. Find the equation of the line for the demand equation. Write your answer in the form p = mx + b. (Hint: Write an equation using two points in the form (x,p)). </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #181743 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=181743\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let x = price of the tile.<BR>\n" );
document.write( "let y = number of tiles sold each month.\r<BR>\n" );
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document.write( "when x = 20, y = 42<BR>\n" );
document.write( "when x = 10, y = 52\r<BR>\n" );
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document.write( "equation of a straight line in slope-intercept form is:\r<BR>\n" );
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document.write( "y = mx+b\r<BR>\n" );
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document.write( "m is the slope and b is the y intercept.\r<BR>\n" );
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document.write( "to find the slope, use the equation m = (y2-y1)/(x2-x1)\r<BR>\n" );
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document.write( "(x1,y1) = (10,52)<BR>\n" );
document.write( "(x2,y2) = (20,42)\r<BR>\n" );
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document.write( "slope equals (52-42)/(10-20) = 10/-10 = -1\r<BR>\n" );
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document.write( "plug this in the general form of the equation to get:\r<BR>\n" );
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document.write( "y = -1*x + b\r<BR>\n" );
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document.write( "substitute for x and y using either of the two points used to find the equation of the line.\r<BR>\n" );
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document.write( "use (20,42)\r<BR>\n" );
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document.write( "equation becomes:\r<BR>\n" );
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document.write( "42 = -1*(20) + b\r<BR>\n" );
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document.write( "solve for b to get:\r<BR>\n" );
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document.write( "b = 62\r<BR>\n" );
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document.write( "equation of your line is:\r<BR>\n" );
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document.write( "y = -1*x + 62\r<BR>\n" );
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document.write( "graph of the equation looks like this:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=graph%28600%2C600%2C-10%2C70%2C-10%2C90%2C-1%2Ax%2B62%29 ALIGN=MIDDLE  ALT=\"graph%28600%2C600%2C-10%2C70%2C-10%2C90%2C-1%2Ax%2B62%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( " </SPAN>\n" );
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