document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=30503>Question 30503</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A marketing firm spent $12,400 in advertisements in January for Alexa's used car emporium. February sales at Alex's were $341,000. In August, the firm spent $8,600 on advertisements, and sales in the following month were $265,000.\r<BR>\n" );
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document.write( "a. write a linear equation relating the amount spent on advertisement x with sales in the following month y. write your answer in slope- intercept form.\r<BR>\n" );
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document.write( "b. use the equation found in part a to predict the sales amount if 10,000 is spent on advertisements in the previous month. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #17198 by </B><A HREF=/tutors/aboutme.mpl?userid=mathtech5><B>mathtech5(4)</B></A><img src=\"/images/stars/iconNewId_16x16.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mathtech5><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=17198\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Set up the points: (12,400 , 341,000) and (86,000 , 265,000)<BR>\n" );
document.write( "Find the slope: (y2 - y1)/ (x2 - x1)<BR>\n" );
document.write( "(265000-341000) / (86000-12400) = 20\r<BR>\n" );
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document.write( "Use the equation y=mx+b: y = 20x + b<BR>\n" );
document.write( "Put a point in for x and y: 265000 = 20(8600) + b<BR>\n" );
document.write( "Now solve for b: 265000=172000 + b<BR>\n" );
document.write( "Subtract 172000 from both sides to get: 93000 = b\r<BR>\n" );
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document.write( "The equation would be : y = 20x + 93,000\r<BR>\n" );
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document.write( "To predict the sales when 10,000 is spent on advertisements, substitute 10,000 in for x: y = 20(10000) + 93000 = 293000\r<BR>\n" );
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document.write( "The predicted sales would be: $293,000 </SPAN>\n" );
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