Question
If $U$ is the universal set with 100 elements, $A$ and $B$ are two sets such that $n(A) = 50$, $n(B) = 60$, and $n(A \cap B) = 20$, then $n(A \cap B') = ?$
If $U$ is the universal set with 100 elements, $A$ and $B$ are two sets such that $n(A) = 50$, $n(B) = 60$, and $n(A \cap B) = 20$, then $n(A \cap B') = ?$