document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1207335>Question 1207335</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi<BR>\n" );
document.write( "Mark bought a number of pens at an average cost of $2.50 He bought another pen for $8.50 and the average cost of the pens became $4.50. How many pens did he buy altogether. <BR>\n" );
document.write( "Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #845157 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=845157\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Mark bought a number of pens at an average cost of $2.50 He bought another pen for $8.50 and the average cost of the pens became $4.50. How many pens did he buy altogether.\r<BR>\n" );
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document.write( "Let Mark buy x pens<BR>\n" );
document.write( "Average cost of pen $2.50\r<BR>\n" );
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document.write( "Total paid by him for  pens 2.50x\r<BR>\n" );
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document.write( "Another pen he bought for $8.50<BR>\n" );
document.write( "Total cost of all pens = 2.50x +8.50\r<BR>\n" );
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document.write( "The average cost now became  $4.50\r<BR>\n" );
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document.write( "Average cost of all pens = total purchase cost /Total number of pens\r<BR>\n" );
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document.write( "4.50 = (2.50x+8.50)/(x+1)\r<BR>\n" );
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document.write( "4.50*(x+1)= 2.50x +8.50\r<BR>\n" );
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document.write( "4.50x +4.50 = 2.50x +8.50\r<BR>\n" );
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document.write( "4.50x-2.50x = 8.50-4.50\r<BR>\n" );
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document.write( "2x = 4\r<BR>\n" );
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document.write( "x=2\r<BR>\n" );
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document.write( "Altogether he bought 3 pens.\r<BR>\n" );
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document.write( "Check<BR>\n" );
document.write( "2*2.50 +8.50=13.50\r<BR>\n" );
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document.write( "number of pens 3\r<BR>\n" );
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document.write( "13.50/3 = 4.50<BR>\n" );
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