Since the difference between the divisors and the respective remainders is not constant, back substitution is the convenient method. None of the given numbers is satisfying the condition.
Divisibility of 11: If the difference of the sum of the digits at odd places and the sum of the digits at even places of a number is zero or a multiple of 11, then that number is divisible by 11.As per divisibility rule of 11, difference = (x + 21) - 18 = x + 3=> x + 3 = 11 => x = 8
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