Answer
$\frac{21}{30}$
Work Step by Step
We know that $P(\text{A or B})=P(A)+P(B)-P(\text{A and B})$.
Hence here: $P(\text{A or B})=P(A)+P(B)-P(\text{A and B})=\frac{12}{30}+\frac{15}{30}-\frac{6}{30}=\frac{21}{30}$
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