If 27 is added to the number, digits are reversed, the number is :

The sum of two digits of a number consisting of two digits is 7. If 27 is added to the number, digits are reversed, the number?

  1. 25
  2. 52
  3. 34
  4. 43
Anurag Mishra Professor Asked on 5th December 2015 in Maths.
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  • 1 Answer(s)

    Answer: (1) 25 

    Explanation:-
    Let the digits be X and Y.

    The sum of two digits of a number consisting of two digits is 7.
    Then, X + Y = 7  …………………………. (1)

    If 27 is added to the number, digits are reversed, 
    Then, 10 X + Y = 27 + 10 Y + X
    9 X – 9 Y = 27 …………………………… (2) 

    Multiply by 9 in equation (1),
    Then, 9 X + 9 Y = 63 ………………….. (3)

    Add equation (2) & (3),
    9 X + 9 X – 9 Y + 9 Y = 27 + 63
    18 X = 90
    X = 90/18
    X = 5

    Put the value of X = 5 in equation (1),
    Then , 5 + Y= 7
     Y = 7 – 5
    Y = 2

    Then, the number is 25.

    Hence, the answer is (1) 25.

    Anurag Mishra Professor Answered on 5th December 2015.
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