document.write( "Question 307067: The sum of the digits of a 2 digit number is 9. If the digits are reversed, the number is decreased by 27. what is the original number? \n" ); document.write( "
Algebra.Com's Answer #219724 by ankor@dixie-net.com(22740)\"\" \"About 
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Let x = the 10's digit
\n" ); document.write( "let y = the units
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\n" ); document.write( "The sum of the digits of a 2 digit number is 9.
\n" ); document.write( "x + y = 9
\n" ); document.write( "y = (9-x); this form for substitution
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\n" ); document.write( "If the digits are reversed, the number is decreased by 27.
\n" ); document.write( "10x + y = the original number
\n" ); document.write( "10y + x = the reversed number
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\n" ); document.write( "Original number - reversed number = 27
\n" ); document.write( "(10x + y) - (10y + x) = 27
\n" ); document.write( "Remove brackets and combine like terms
\n" ); document.write( "10x - x - 10y + y = 27
\n" ); document.write( "9x - 9y = 27
\n" ); document.write( "Simplify, divide by 9
\n" ); document.write( "x - y = 3
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\n" ); document.write( "Substitute (9-x) for y
\n" ); document.write( "x - (9-x) = 3
\n" ); document.write( "x + x - 9 = 3
\n" ); document.write( "2x = 3 + 9
\n" ); document.write( "2x = 12
\n" ); document.write( "x = 6
\n" ); document.write( "then
\n" ); document.write( "y = 9 - 6
\n" ); document.write( "y = 3
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\n" ); document.write( "63 is the original two digit number
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\n" ); document.write( "Check 63 - 36 = 27 \r
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