document.write( "Question 1156730: The sum of john and lizas age is 21. If john is 3 years younger than liza, how old are john & liza?
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Algebra.Com's Answer #779479 by ikleyn(52781) $\"\"$ $\"About$

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document.write( "Replace Lisa (MENTALLY) by other person Mona, who is 3 years younger than Liza.\r\n" );
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document.write( "Then John and Mona are of the same age, and the sum of their ages is 21-3 = 18.\r\n" );
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document.write( "Therefore, John is 18/2= 9 years old and Mona is 9 years old, too.\r\n" );
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document.write( "From this point, you immediately conclude that Lisa is 9+3 = 12 years old.\r\n" );
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document.write( "ANSWER.  The ordered pair (x,y) is (9,12).\r\n" );
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\n" ); document.write( "\n" ); document.write( "At this point, you may forget about this person Mona, since it was \"imaginary\" person, introduced to facilitate the solution, ONLY.\r
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