document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=949818>Question 949818</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A father is three times as old as his son was n years ago.  At that same time (n years ago), the father was twice as old as his son will be two years from now.  Find the present age of each is they sum to 55. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #579960 by </B><A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><B>ankor@dixie-net.com(22740)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ankor@dixie-net.com><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=ankor@dixie-net.com><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=579960\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> f = father's present age<BR>\n" );
document.write( "s = son's present age<BR>\n" );
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document.write( "Write an equation for each statement<BR>\n" );
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document.write( "A father is three times as old as his son was n years ago.<BR>\n" );
document.write( "f = 3(s - n)<BR>\n" );
document.write( "f = 3s - 3n<BR>\n" );
document.write( "f + 3n = 3s<BR>\n" );
document.write( " At that same time (n years ago), the father was twice as old as his son will be two years from now.<BR>\n" );
document.write( "f - n = 2(s + 2)<BR>\n" );
document.write( "f - n = 2s + 4<BR>\n" );
document.write( "multiply this by 3, add to the 1st equation<BR>\n" );
document.write( "3f - 3n = 6s + 12<BR>\n" );
document.write( "f + 3n = 3s<BR>\n" );
document.write( "----------------adding in eliminates n<BR>\n" );
document.write( "4f = 9s + 12<BR>\n" );
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document.write( " Find the present age of each is they sum to 55.<BR>\n" );
document.write( " f + s = 55<BR>\n" );
document.write( "f = (55-s)<BR>\n" );
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document.write( "Replace f with (55-s) in the 4f = 9s + 12 equation<BR>\n" );
document.write( "4(55-s) = 9s + 12<BR>\n" );
document.write( "220 - 4s = 9s + 12<BR>\n" );
document.write( "220 -12 = 9s + 4s<BR>\n" );
document.write( "208 = 13s <BR>\n" );
document.write( "s = 208/13<BR>\n" );
document.write( "s = 16 is the son's age<BR>\n" );
document.write( "then<BR>\n" );
document.write( "55 - 16 = 39 is father's age<BR>\n" );
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document.write( ";<BR>\n" );
document.write( "Check this out, find n<BR>\n" );
document.write( "f = 3(s - n)<BR>\n" );
document.write( "39 = 3(16-n)<BR>\n" );
document.write( "39 = 48 - 3n<BR>\n" );
document.write( "3n = 48 - 39<BR>\n" );
document.write( "n = 9/3<BR>\n" );
document.write( "n = 3<BR>\n" );
document.write( "\"At that same time (n years ago), the father was twice as old as his son will be two years from now.\"<BR>\n" );
document.write( "39 - 3 = 2(18)<BR>\n" );
document.write( "36 = 36 confirms our solutions\r<BR>\n" );
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document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );