document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=244886>Question 244886</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A box containing 40 nails weighs 175 grams. The same box with 20 nails weighs 95 grams. What is the sum of the weight of the box and one nail?\r<BR>\n" );
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document.write( "(A) 4 (B) 9.5 (C) 15 (D) 19 (E) 69.7 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #179034 by </B><A HREF=/tutors/aboutme.mpl?userid=jsmallt9><B>jsmallt9(3758)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jsmallt9><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=179034\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let n = the weight of a nail<BR>\n" );
document.write( "Let b = the weight of the box<BR>\n" );
document.write( "Then<BR>\n" );
document.write( "40n + b = 175<BR>\n" );
document.write( "20n + b = 95<br><BR>\n" );
document.write( "We now have a system of two equations in two variables. There is a large variety of methods to solve this:<ul><li>Graphing</li><li>Substitution</li><li>Elimination/Linear Combination/Addition</li><li>Cramer's Rule</li><li>and a variety of matrix-based methods</li></ul><BR>\n" );
document.write( "This system is solved fairly easily with either the Substitution or Linear Combination methods. I'll use the later:<BR>\n" );
document.write( "Subtract the second equation from the first which results in:<BR>\n" );
document.write( "20n = 80<BR>\n" );
document.write( "Divide by 20<BR>\n" );
document.write( "n = 4<BR>\n" );
document.write( "Use this value in one of the original equations to find b:<BR>\n" );
document.write( "40(4) + b = 175<BR>\n" );
document.write( "160 + b = 175<BR>\n" );
document.write( "b = 15<br><BR>\n" );
document.write( "This makes the sum: 4 + 15 = 19. Answer: D. </SPAN>\n" );
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