#### Answer

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

#### Work Step by Step

The Counting Formula says that for finite sets $A$ and $B$: $n(A\cup B)=n(A)+n(B)-n(A\cap B)$.

Published by
Pearson

ISBN 10:
0-32193-104-1

ISBN 13:
978-0-32193-104-7

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

The Counting Formula says that for finite sets $A$ and $B$: $n(A\cup B)=n(A)+n(B)-n(A\cap B)$.

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