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document.write( "Twice the sum of the digits of a two-digit number is 14. The original number subtracted from the number formed when the digits are reversed is 27. What is the original number?
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document.write( "Correct answer:
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document.write( "Since the original number, when SUBTRACTED from the reversed number, is 27, it's obvious that the reversed number will be LARGER than the original number.\r\n" );
document.write( "Therefore, the original number CANNOT be 52. \r\n" );
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document.write( "Twice the sum of the 2 digits is 24, so sum of the 2 digits is 7.\r\n" );
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document.write( "Let tens digit be T\r\n" );
document.write( "Then U (units digit) = 7 - T \r\n" );
document.write( "Original number: 10T + U\r\n" );
document.write( "Reversed number: 10U + T\r\n" );
document.write( "We then get: 10U + T - (10T + U) = 27\r\n" );
document.write( "10U + T - 10T - U = 27\r\n" );
document.write( "9U - 9T = 27_____9(U - T) = 9(3)_____U - T = 3 ----- eq (i)\r\n" );
document.write( "7 - T - T = 3 ------ Substituting 7 - T for U in eq (i)\r\n" );
document.write( "- T - T = 3 - 7 \r\n" );
document.write( "- 2T = - 4\r\n" );
document.write( "Tens digit or
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document.write( "Units digit: 7 - 2, or 5
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