$A$ and $B$ are two sets such that $n(A \cup B)=36, n(A \cap B)=16$ and $n(A-B)=15$. Then $n(B)=$

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Professor PC Thomas Classes · Answer

$n(A) = n(A-B) + n(A \cap B) = 15+16=31$. $n(B) = n(A \cup B) - n(A) + n(A \cap B) = 36 - 31 + 16 = 21$.