document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=55136>Question 55136</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Bob invested $20,000, part at 14% and part at 13%.  If the total interest at the end of the year is $2,720, how much did he invest at 14%? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #37399 by </B><A HREF=/tutors/aboutme.mpl?userid=Hook><B>Hook(36)</B></A><img src=\"/images/stars/stars-07.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Hook><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=37399\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Lets call x the amount that Bob invested at 14% and y the amount that he invested at 13%. \r<BR>\n" );
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document.write( "Combined, Bob invested 20 grand, so we have<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+%2B+y+=+20000 ALIGN=MIDDLE  ALT=\"x+%2B+y+=+20000\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Additionally, we know that the sum of the amount that Bob invested at 14% and 13% is equal to $2720. In math-speak, that says:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.14x%2B.13y+=+2720 ALIGN=MIDDLE  ALT=\".14x%2B.13y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "So we have the following system of equations:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+%2B+y+=+20000 ALIGN=MIDDLE  ALT=\"x+%2B+y+=+20000\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.14x+%2B+.13y+=+2720 ALIGN=MIDDLE  ALT=\".14x+%2B+.13y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "My strategy will be to use the substitution method. \r<BR>\n" );
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document.write( "Starting with<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+%2B+y+=+20000 ALIGN=MIDDLE  ALT=\"x+%2B+y+=+20000\"   DISABLED_style= \"max-width:90%; height:auto;\" > and solving for x, I get<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+20000-y ALIGN=MIDDLE  ALT=\"x+=+20000-y\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "I'll plop that into the second equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.14x+%2B+.13y+=+2720 ALIGN=MIDDLE  ALT=\".14x+%2B+.13y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.14%2820000-y%29+%2B+.13y+=+2720 ALIGN=MIDDLE  ALT=\".14%2820000-y%29+%2B+.13y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2800-.14y%2B.13y+=+2720 ALIGN=MIDDLE  ALT=\"2800-.14y%2B.13y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2800+-+.01y+=+2720 ALIGN=MIDDLE  ALT=\"2800+-+.01y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=-.01y+=+-80 ALIGN=MIDDLE  ALT=\"-.01y+=+-80\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=8000 ALIGN=MIDDLE  ALT=\"y+=8000\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Great! Bob invested $8000 at 13%\r<BR>\n" );
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document.write( "I'll put that back into <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+20000-y ALIGN=MIDDLE  ALT=\"x+=+20000-y\"   DISABLED_style= \"max-width:90%; height:auto;\" > to find x<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+20000-8000 ALIGN=MIDDLE  ALT=\"x+=+20000-8000\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+12000 ALIGN=MIDDLE  ALT=\"x+=+12000\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "So the answer is Bob invested $12000 at 14%\r<BR>\n" );
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document.write( "CHECK:\r<BR>\n" );
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document.write( "I'll check my work by plugging x = 12000 and y = 8000 into the second equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.14x%2B.13y+=+2720 ALIGN=MIDDLE  ALT=\".14x%2B.13y+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=.14%2812000%29%2B.13%288000%29+=+2720 ALIGN=MIDDLE  ALT=\".14%2812000%29%2B.13%288000%29+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1680+%2B+1040+=+2720 ALIGN=MIDDLE  ALT=\"1680+%2B+1040+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2720+=+2720 ALIGN=MIDDLE  ALT=\"2720+=+2720\"   DISABLED_style= \"max-width:90%; height:auto;\" >...check! </SPAN>\n" );
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