document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=170750>Question 170750</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/0395977258/algebrahomeworkh>algebra and trigonometry</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> The sum of two numbers is 20.  The difference of their squares is 120.  What are the numbers? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #126050 by </B><A HREF=/tutors/aboutme.mpl?userid=checkley77><B>checkley77(12844)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=checkley77><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=126050\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> X+Y=20 OR X=20-Y<BR>\n" );
document.write( "X^2-Y^2=120<BR>\n" );
document.write( "(20-Y)^2-Y^2=120<BR>\n" );
document.write( "400-40Y+Y^2=120<BR>\n" );
document.write( "-40Y=120-400<BR>\n" );
document.write( "-40Y=-280<BR>\n" );
document.write( "Y=-280/-40<BR>\n" );
document.write( "Y=7 ans.<BR>\n" );
document.write( "X+7=20<BR>\n" );
document.write( "X=20-7<BR>\n" );
document.write( "X=13 ans.<BR>\n" );
document.write( "Proof:<BR>\n" );
document.write( "13^2-7^2=120<BR>\n" );
document.write( "169-49=120<BR>\n" );
document.write( "120=120<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );