document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=136749>Question 136749</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Translate the following into a system of equations, then solve it:\r<BR>\n" );
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document.write( "A customer walks into an electronics store and buys five MP3 players and eight sets of headphones, paying $840. A second customer buys three MP3 players and four sets of headphones, and pays $480. How much does an MP3 player cost? How much does a set of headphones cost?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #100239 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=100239\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A customer walks into an electronics store and buys five MP3 players and eight sets of headphones, paying $840. A second customer buys three MP3 players and four sets of headphones, and pays $480. How much does an MP3 player cost? How much does a set of headphones cost? <BR>\n" );
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document.write( "Let x = cost of a MP3<BR>\n" );
document.write( "Let y = cost of a headphone<BR>\n" );
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document.write( "Write an equation for each transaction:<BR>\n" );
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document.write( "5x + 8y = 840<BR>\n" );
document.write( "3x + 4y = 480<BR>\n" );
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document.write( "Multiply the 2nd equation by 2, subtract the 1st equation from that:<BR>\n" );
document.write( "6x + 8y = 960<BR>\n" );
document.write( "5x + 8y = 840<BR>\n" );
document.write( "-----------------subtracting eliminates y, find x<BR>\n" );
document.write( "1x + 0y = 120<BR>\n" );
document.write( "x = $120 cost of each MP3<BR>\n" );
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document.write( "Find y using the 1st original equation, substitute 120 for x<BR>\n" );
document.write( "5(120) + 8y = 840<BR>\n" );
document.write( "600 + 8y = 840<BR>\n" );
document.write( "8y = 840 - 600<BR>\n" );
document.write( "y = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=240%2F8 ALIGN=MIDDLE  ALT=\"240%2F8\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "y = $30 cost of each headphone<BR>\n" );
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document.write( "Check solution in 2nd original equation:<BR>\n" );
document.write( "3(120) + 4(30) = 480<BR>\n" );
document.write( "360 + 120 = 480; confirms our solutions </SPAN>\n" );
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