Let \( S = \{1, 2, 3, 4, 5, 6, 7, 8, 9\} \). Let \( x \) be the number of \( 9 \)-digit numbers formed using the digits of the set \( S \) such that only one digit is repeated and it is repeated exactly twice. Let \( y \) be the number of \( 9 \)-digit numbers formed using the digits of the set \( S \) such that only two digits are repeated and each of these is repeated exactly twice. Then,
