Question

$A$ and $B$ are two sets such that $n(A$ $\cup$ $B)=25$, $n(A^{\prime }$ $\cap$ $B)=8$ and $n(A$ $\cap$ $B^{\prime })=9$.

Use venn -diagram to find $n(B-A)$.

Answer 1

$n(A^{\prime }\cap B)$ denotes only $B$ which is same as $n(B-A)$
From the figure, $n(B-A)=n(A^{\prime }\cap B)=8$