document.write( "Question 246125: Mary is the younger than her sister Joan. The sum of their age is 15. Twice Joan’s age is three times the sum of 5 and Mary’s age. How old are the two sisters? \n" ); document.write( "
Algebra.Com's Answer #179760 by marcsam823(57)\"\" \"About 
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Let x = Mary's age
\n" ); document.write( "Let y = Joan's age
\n" ); document.write( "Let x + y = 15\r
\n" ); document.write( "\n" ); document.write( "Solve for y:\r
\n" ); document.write( "\n" ); document.write( "y = 15 - x\r
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\n" ); document.write( "\n" ); document.write( "Translate the words into algebra:\r
\n" ); document.write( "\n" ); document.write( "Twice Joan's age = 2y or 2(15-x)
\n" ); document.write( "3 times the sum of 5 and Mary's age = 3(5 + x)\r
\n" ); document.write( "\n" ); document.write( "Set these two expressions equal to each other:\r
\n" ); document.write( "\n" ); document.write( "2(15 - x) = 3(5 + x)\r
\n" ); document.write( "\n" ); document.write( "Solve:\r
\n" ); document.write( "\n" ); document.write( "30 - 2x = 15 + 3x\r
\n" ); document.write( "\n" ); document.write( "15 = 5x\r
\n" ); document.write( "\n" ); document.write( "x = 3 \r
\n" ); document.write( "\n" ); document.write( "15 - x = y = 12\r
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\n" ); document.write( "\n" ); document.write( "Mary's age is 3
\n" ); document.write( "Joan's age is 12\r
\n" ); document.write( "\n" ); document.write( "This solution also satisfies teh condition that Mary be younger than Joan \r
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