document.write( "Question 994596: A boy is two years more than twice as old as his mother. The sum of their ages is nine years more than the age of their sister. If the sister is three years younger than the older boy, find the age of each. \n" ); document.write( "
Algebra.Com's Answer #613633 by josgarithmetic(39617)\"\" \"About 
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b, boy
\n" ); document.write( "m, his mother
\n" ); document.write( "s, sister of boy
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\n" ); document.write( "MUST expect \"b%3Cm\";\r
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\n" ); document.write( "\n" ); document.write( "\"system%28b=2%2B2%2Am%2Cb%2Bm=9%2Bs%2Cs=-3%2Bb%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"system%282m-b=-2%2Cm%2Bb-s=9%2Cb-s=3%29\"\r
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\n" ); document.write( "\n" ); document.write( "Use the last two equations to eliminate s, and have a simpler system.
\n" ); document.write( "\"-s=3-b\"
\n" ); document.write( "\"s=b-3\"
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\n" ); document.write( "\"m%2Bb-%28b-3%29=9\"
\n" ); document.write( "\"m%2Bb-b%2B3=9\"
\n" ); document.write( "\"m%2B3=9\"
\n" ); document.write( "\"highlight%28m=6%29\"------?
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\n" ); document.write( "Use the middle equation of the system to eliminate m.
\n" ); document.write( "\"m%2Bb-s=9\"
\n" ); document.write( "\"6%2Bb-s=9\"
\n" ); document.write( "\"b-s=6\"---------This creates a contradiction.\r
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\n" ); document.write( "\n" ); document.write( "This result shows b-s=6 and one of the system equations was b-s=3. They cannot both be part of the system of equations. One of them may be true, but then this makes the other false.\r
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\n" ); document.write( "\n" ); document.write( "Your problem description is wrong.
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