document.write( "Question 980579: -Adrian and Betty have been teaching for a total of 36 years.\r
\n" ); document.write( "\n" ); document.write( " -Charlie and Betty have been teaching for a total of 22 years.\r
\n" ); document.write( "\n" ); document.write( " -Charlie and Adrian have been teaching for a total of 28 years.\r
\n" ); document.write( "\n" ); document.write( "How long has each been teaching? \n" ); document.write( "

Algebra.Com's Answer #601822 by MathTherapy(10810) $\"\"$ $\"About$

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\n" ); document.write( " -Adrian and Betty have been teaching for a total of 36 years.\r
\n" ); document.write( "\n" ); document.write( " -Charlie and Betty have been teaching for a total of 22 years.\r
\n" ); document.write( "\n" ); document.write( " -Charlie and Adrian have been teaching for a total of 28 years.\r
\n" ); document.write( "\n" ); document.write( "How long has each been teaching?
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Let number of years Adrian, Betty, and Charlie have been teaching be A, B, and C, respectively
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document.write( "We then get: 
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document.write( "A + B = 36______B = 36 - A -------- eq (i)
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document.write( "C + B = 22 -------- eq (ii)
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document.write( "C + A = 28 -------- eq (iii)\r
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document.write( "C + 36 - A = 22 ----- Substituting 36 - A for B in eq (ii) 
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document.write( "C - A = 22 - 36 
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document.write( "C - A = - 14 -------- eq (iv)
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document.write( "2C = 14 ------------- Adding eqs (iii) & (iv)
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document.write( "C, or amount of time Charlie has been teaching = , or  years\r
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document.write( "7 + B = 22 ---------- Substituting 7 for C in eq (ii)
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document.write( "B = 22 - 7
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document.write( "B, or amount of time Betty has been teaching =  years\r
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document.write( "7 + A = 28 ---------- Substituting 7 for C in eq (iii)
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document.write( "A = 28 - 7
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document.write( "A, or amount of time Adrian has been teaching =  years \n" );
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