# Let A and B be two sets that

Question:

Let $A$ and $B$ be two sets that $n(A)=16, n(B)=14, n(A \cup B)=25$. Then, $n(A \cap B)$ is equal to

(a) 30

(b) 50

(c) 5

(d) none of these

Solution:

We know:

$n(A \cup B)=n(A)+n(B)-n(A \cap B)$

Now,

$n(A \cap B)=n(A)+n(B)-n(A \cup B)$

$=16+14-25$

$=5$