#### Answer

Fill the blanks with
... mutually exclusive...
... $P(A)+P(B)$ .

#### Work Step by Step

If it is impossible for events $A$ and $B$ to occur simultaneously, the events are mutually exclusive.
If $A$ and $B$ are mutually exclusive events, then:
$P$ ( A or B ) $=P(A)+P(B)$.
-----------
Fill the blanks with
... mutually exclusive...
... $P(A)+P(B)$ .