If X and Y are sets of integers, X # Y denotes the set of integers that belong to set X or set Y, but not both. If X consists of 16 integers, Y consists of 18 integers, and 6 of the integers are in both X and Y, then X # Y consists of how many integers? Choose one
A) 6  B) 16  C) 22  D) 30  E) 174

Rationale: "the number of integers that belong to set x only is 16 - 6 = 10 ; the number of integers that belong to set y only is 18 - 6 = 12 ; the number of integers that belong to set x or set y , but not both is 10 + 12 = 22 . answer : c"
Answer: C