document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1048479>Question 1048479</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Jack is 5 years older than his sister. The sum of their ages is 21. How old are Jack and his sister? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #664084 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52794)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=664084\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
document.write( "Jack is 5 years older than his sister. The sum of their ages is 21. How old are Jack and his sister?<BR>\n" );
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document.write( "<B>Solution 1</U> (using two equations in two unknowns)\r<BR>\n" );
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document.write( "The condition says that\r\n" );
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document.write( "J - S =  5,   (1)   (\"Jack is 5 years older than his sister\")\r\n" );
document.write( "J + S = 21.   (2)   (\"The sum of their ages is 21\")\r\n" );
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document.write( "Add the equations (1) and (2)  (both sides). You will get\r\n" );
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document.write( "2J = 5 + 21  --->  2J = 26  --->  J = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=26%2F2 ALIGN=MIDDLE  ALT=\"26%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 13.\r\n" );
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document.write( "Thus you found Jack's age. He is 13 years old.\r\n" );
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document.write( "Then his sister is 13 - 5 = 8 years old.\r\n" );
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document.write( "<U>Answer</U>.  Jack is is 13 years old.  His sister is 8 years old.\r\n" );
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document.write( "<U>Check</U>.  Please check yourself.\r\n" );
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document.write( "<U>Solution 2</U>  (using one equation)\r<BR>\n" );
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document.write( "Let J be Jack's age.\r\n" );
document.write( "The Jack's sister age is (J-5) years.\r\n" );
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document.write( "The sum of their ages is 21, so\r\n" );
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document.write( "J + (J-5) = 21.\r\n" );
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document.write( "Simplify and solve for J.\r\n" );
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document.write( "2J - 5 = 21  --->  2J = 21 + 5 = 26  --->  J = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=26%2F2 ALIGN=MIDDLE  ALT=\"26%2F2\"   DISABLED_style= \"max-width:90%; height:auto;\" > = 13.\r\n" );
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document.write( "We obtain the same result:  Jack is 13 years old; his sister is 8 years old.\r\n" );
document.write( "</PRE>\r<BR>\n" );
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document.write( "There is a bunch of lessons on age word problems \r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=http://www.algebra.com/algebra/homework/word/age/Age-problems-and-their-solutions.lesson>Age problems and their solutions</A>\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=http://www.algebra.com/algebra/homework/word/age/Fresh-formulation-of-a-traditional-age-problem.lesson>A fresh formulation of a traditional age problem</A>\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=http://www.algebra.com/algebra/homework/word/age/Really-intricate-age-word-problem.lesson>Really intricate age word problem</A>\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/word/age/Selected-age-word-problems-from-the-archive.lesson>Selected age word problems from the archive</A>\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/word/age/04-OVERVIEW-of-lessons-on-age-problems.lesson>OVERVIEW of lessons on age problems</A>\r<BR>\n" );
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document.write( "in this site.\r<BR>\n" );
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document.write( "Read them and become an expert in solving age problems.\r<BR>\n" );
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document.write( "Also, you have this free of charge online textbook in ALGEBRA-I in this site\r<BR>\n" );
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document.write( "&nbsp;&nbsp;&nbsp;&nbsp;- <A  rel=nofollow HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.\r<BR>\n" );
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document.write( "It contains a lot of other word problems and many other interesting and useful things.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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