If A and B are two finite sets, then n(A) + n(B) is equal to _________
If A and B are two finite sets, then
\[ n(A \cup B) = n(A) + n(B) – n(A \cap B) \]
Therefore,
\[ n(A) + n(B) = n(A \cup B) + n(A \cap B) \]
Answer
\[ \boxed{n(A \cup B) + n(A \cap B)} \]