## Precalculus (10th Edition)

$0.7$
We know that by the addition rule of probabilities $P(A\cup B)=P(A)+P(B)-P(A\cap B)$ If $A$ and $B$ are mutually exclusive, then $P(A\cap B)=0.$ Hence , $P(A\cup B)=0.25+0.45-0=0.7$