3. Number of elements in the union of sets

If \(n(A) = 55\), \(n(B) = 31\), \(n(C) = 25\), \(n(A \cap B) = 19\), \(n(B \cap C) = 20\), \(n(A \cap C) = 18\), and \(n(A \cap B \cap C) = 5\), then find out \(n(A \cup B \cup C)\).

 

\(n(A \cup B \cup C)\) \(=\) .