document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=442283>Question 442283</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 is the number? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #305032 by </B><A HREF=/tutors/aboutme.mpl?userid=ilana><B>ilana(307)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ilana><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=305032\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If the digit is ab, then from the first statement you know that a + b = 7.<BR>\n" );
document.write( "For the second statement, remember that ab = 10a + b (like 23 = 10*2 + 3).<BR>\n" );
document.write( "So 10b + a = 10a + b + 9.<BR>\n" );
document.write( "Using the first equation, we know a = 7 - b. Substitute 7 - b for a in the last equation.<BR>\n" );
document.write( "10b + (7 - b) = 10(7 - b) + b + 9<BR>\n" );
document.write( "10b + 7 - b = 70 - 10b + b + 9<BR>\n" );
document.write( "9b + 7 = 79 - 9b<BR>\n" );
document.write( "18b = 72<BR>\n" );
document.write( "b = 4<BR>\n" );
document.write( "a = 7 - 4 = 3<BR>\n" );
document.write( "The number is 34. You can test this number in the given statements to check. </SPAN>\n" );
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