document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1005425>Question 1005425</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Five years ago, a father was seven times as old as his son. Five years hence, the father will be three times as old as his son. Find their own and present ages. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #622157 by </B><A HREF=/tutors/aboutme.mpl?userid=fractalier><B>fractalier(6550)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=fractalier><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/cgi-bin/show-face.mpl?user=fractalier><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=622157\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Call their ages NOW, f and s.  Then we have<BR>\n" );
document.write( "f - 5 = 7(s - 5)  and<BR>\n" );
document.write( "f + 5 = 3(s + 5)<BR>\n" );
document.write( "Solve the first one for f and substitute that into the second equation...<BR>\n" );
document.write( "f = 7(s - 5) + 5 = 7s - 35 + 5 = 7s - 30<BR>\n" );
document.write( "and now substituting<BR>\n" );
document.write( "7s - 30 + 5 = 3(s + 5)<BR>\n" );
document.write( "7s - 25 = 3s + 15<BR>\n" );
document.write( "4s - 25 = 15<BR>\n" );
document.write( "4s = 40<BR>\n" );
document.write( "s = 10<BR>\n" );
document.write( "f is then 40. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );