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    Question

    In a two digit positive number, the digit in the

    unit’s place is equal to the square of the digit in ten’s place, and the difference between the number and the number obtained by interchanging the digits is 54. What is 60% of the original number?
    A 23.4 Correct Answer Incorrect Answer
    B 19.8 Correct Answer Incorrect Answer
    C 15.9 Correct Answer Incorrect Answer
    D 28.5 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the number = 10x + x 2 According to the question, 10x + x2 - (10x2 - x) = 54 9(x2 - x) = 54 x 2 - x = 6 x2 - x – 6 = 0 ( x - 3) (x + 2) = 0 x = 3 or x = -2 Number = 39 [x≠ 2] => 60% of 39 = (60/100)× 39 = 23.4

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