document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=941095>Question 941095</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The sum of ahmed's age and his son age is 50. Last year ahmed was three times as old as his son. How old is ahmed this year? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #573700 by </B><A HREF=/tutors/aboutme.mpl?userid=laoman><B>laoman(51)</B></A><img src=\"/images/stars/stars-08.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=laoman><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=laoman><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=573700\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Let ahmed's age be a, let the son's age be s<BR>\n" );
document.write( "From first statement, a + s = 50<BR>\n" );
document.write( "From second statement, a-1 = 3*(s-1)<BR>\n" );
document.write( "a-1 = 3s - 3<BR>\n" );
document.write( "Solving these equations<BR>\n" );
document.write( "a+s = 50<BR>\n" );
document.write( "a - 3s = -2<BR>\n" );
document.write( "<TABLE  BORDER=1>\n" );
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document.write( " <TR><TD  ALIGN=MIDDLE>Solved by <A  rel=nofollow HREF=http://wiki.algebra.com/index.php/Tutoring_-_pluggable_solvers>pluggable</A> solver: <A  rel=nofollow HREF=linear_substitution.solver>SOLVE linear system by SUBSTITUTION</A></TD></TR>\n" );
document.write( "<TR><TD  ALIGN=LEFT>Solve:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+system%28+%0D%0A++++1%5Ca+%2B+1%5Cs+=+50%2C%0D%0A++++1%5Ca+%2B+-3%5Cs+=+-2+%29%0D%0A++ ALIGN=MIDDLE  ALT=\"+system%28+%0D%0A++++1%5Ca+%2B+1%5Cs+=+50%2C%0D%0A++++1%5Ca+%2B+-3%5Cs+=+-2+%29%0D%0A++\"   DISABLED_style= \"max-width:90%; height:auto;\" >We'll use substitution. After moving 1*s to the right, we get:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2Aa+=+50+-+1%2As ALIGN=MIDDLE  ALT=\"1%2Aa+=+50+-+1%2As\"   DISABLED_style= \"max-width:90%; height:auto;\" >, or <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a+=+50%2F1+-+1%2As%2F1 ALIGN=MIDDLE  ALT=\"a+=+50%2F1+-+1%2As%2F1\"   DISABLED_style= \"max-width:90%; height:auto;\" >. Substitute that<BR>\n" );
document.write( "  into another equation:<BR>\n" );
document.write( "  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2A%2850%2F1+-+1%2As%2F1%29+%2B+-3%5Cs+=+-2 ALIGN=MIDDLE  ALT=\"1%2A%2850%2F1+-+1%2As%2F1%29+%2B+-3%5Cs+=+-2\"   DISABLED_style= \"max-width:90%; height:auto;\" > and simplify: So, we know that s=13. Since <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=a+=+50%2F1+-+1%2As%2F1 ALIGN=MIDDLE  ALT=\"a+=+50%2F1+-+1%2As%2F1\"   DISABLED_style= \"max-width:90%; height:auto;\" >, a=37.<BR>\n" );
document.write( "  <BR>\n" );
document.write( "  Answer: <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=system%28+a=37%2C+s=13+%29 ALIGN=MIDDLE  ALT=\"system%28+a=37%2C+s=13+%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.<BR>\n" );
document.write( "  </TD></TR>\n" );
document.write( "</TABLE><BR>\n" );
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document.write( "Therefore, Ahmed is 37 years old this year </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );