document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=847420>Question 847420</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A change machine at an arcade gives change for $1 bills and $5 bills. If during a particular day, 200 bills were inserted into the machine and the total vaule was $300, how many $1 bills were inserted into the machine? <BR>\n" );
document.write( "A) 25 <BR>\n" );
document.write( "B)75 <BR>\n" );
document.write( "C)125 <BR>\n" );
document.write( "D)175 <BR>\n" );
document.write( " Can you please show me how to solve it? I already know the answer is D- 175 but I just don't know how to get that.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #510407 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=510407\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let \r<BR>\n" );
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document.write( "x = number of $1 bills<BR>\n" );
document.write( "y = number of $5 bills\r<BR>\n" );
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document.write( "There are 200 bills of just $1 and $5 bills. So the two must add to 200\r<BR>\n" );
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document.write( "x + y = 200\r<BR>\n" );
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document.write( "Solve for y to get y = 200 - x\r<BR>\n" );
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document.write( "If you have x $1 bills and y $5 bills, then you'll have a total of x + 5y dollars. But we know this total is also equal to $300, so\r<BR>\n" );
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document.write( "x + 5y = 300\r<BR>\n" );
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document.write( "Replace each copy of y with 200 - x (since above we know that y = 200 - x) to get\r<BR>\n" );
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document.write( "x + 5<font color=\"red\">y</font> = 300\r<BR>\n" );
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document.write( "x + 5(<font color=\"red\">y</font>) = 300\r<BR>\n" );
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document.write( "x + 5(<font color=\"red\">200 - x</font>) = 300\r<BR>\n" );
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document.write( "x + 5(200 - x) = 300\r<BR>\n" );
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document.write( "Notice how y is completely gone now. Now solve for x\r<BR>\n" );
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document.write( "x + 5(200 - x) = 300\r<BR>\n" );
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document.write( "x + 5(200) + 5(-x) = 300\r<BR>\n" );
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document.write( "x + 1000 - 5x = 300\r<BR>\n" );
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document.write( "-4x + 1000 = 300\r<BR>\n" );
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document.write( "-4x = 300 - 1000\r<BR>\n" );
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document.write( "-4x = -700\r<BR>\n" );
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document.write( "x = -700/(-4)\r<BR>\n" );
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document.write( "x = 175\r<BR>\n" );
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document.write( "We could stop here, but let's keep going to find y\r<BR>\n" );
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document.write( "y = 200 - x\r<BR>\n" );
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document.write( "y = 200 - 175\r<BR>\n" );
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document.write( "y = 25\r<BR>\n" );
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document.write( "This bit is extra, but it helps to know how to find it (if asked).\r<BR>\n" );
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document.write( "Answer:\r<BR>\n" );
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document.write( "Since x = 175, this means that there are <font size = 5 color=\"red\">175</font> one dollar bills.\r<BR>\n" );
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document.write( "Note: if you forget what x is, look back up at the definitions above. This is why it helps to set these up first.\r<BR>\n" );
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