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    A two-digit number is 4 times the sum of its digits and twice the product of the digits. The number is:
    Question

    A two-digit number is 4 times the sum of its digits and twice the product of the digits. The number is:

    A.

    63

    B.

    45

    C.

    36

    D.

    54

    Correct option is C

    Given:

    Let the two-digit number be 10x + y, where x is the tens digit and y is the units digit.
    Then:

    Number = 4 × (x + y)

    Number = 2 × (x × y)

    Formula used:
    10x + y = 4(x + y) ...(1)
    10x + y = 2xy ...(2)

    Solution:
    From (1):
    10x + y = 4x + 4y
    => 6x - 3y = 0
    => 2x = y ...(A)

    Substitute (A) in (2):
    10x + y = 2xy
    => 10x + 2x = 2x × 2x
    => 12x = 4x²
    => 4x² - 12x = 0
    => 4x(x - 3) = 0
    => x = 0 or x = 3

    Reject x = 0 (since the number wouldn't be two-digit)
    So, x = 3 => y = 2x = 6
    Number = 10x + y = 30 + 6 = 36

    Correct answer is (c)

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