Answer
$n(U)[n(A\cup B)-n(A\cap B)]=12*(7-2)=60$
Work Step by Step
$n(A\cup B)$ is the number of distinct elements which are in $A$, in $B$, or in both $A$ and $B$.
We can see that $n(A\cup B)=7$
$n(A\cap B)$ is the number of elements of $A$ that are also elements of $B$.
We can see that $n(A\cap B)=2$
$n(U)$ is the number of all elements in the diagram.
We can see that $n(U)=12$
Therefore:
$n(U)[n(A\cup B)-n(A\cap B)]=12*(7-2)=60$
