document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=381751>Question 381751</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The sum of the digits of a certain two-digit number is 7.  Reversing its digits increases the number by 9. what are the two equations?<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #270754 by </B><A HREF=/tutors/aboutme.mpl?userid=lar><B>lar(3)</B></A><img src=\"/images/stars/iconNewId_16x16.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lar><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=270754\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let the digits of the number be x and y.<BR>\n" );
document.write( "So the number is xy (note: this does not mean x times y).<BR>\n" );
document.write( "x+y=7 and yx=xy+9<BR>\n" );
document.write( "In order for yx to equal xy+9, x=y-1.<BR>\n" );
document.write( "Now we have the two equations x+y=7 and x=y-1.<BR>\n" );
document.write( "x+y=7 -> x=7-y<BR>\n" );
document.write( "y-1=7-y<BR>\n" );
document.write( "2y=8<BR>\n" );
document.write( "y=4<BR>\n" );
document.write( "Plug that into one of the original equations: x+4=7<BR>\n" );
document.write( "x=3<BR>\n" );
document.write( "The number is 34.<BR>\n" );
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