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प्रश्न
Let A and B be two sets such that : \[n \left( A \right) = 20, n \left( A \cup B \right) = 42 \text{ and } n \left( A \cap B \right) = 4\] \[n \left( A - B \right)\]
उत्तर
Given:
\[n \left( A \right) = 20, n \left( A \cup B \right) = 42 \text{ and } n \left( A \cap B \right) = 4\]
\[ n(A - B) = n(A) - n(A \cap B)\]
\[ \Rightarrow n(A - B) = 20 - 4 = 16\]
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