If $P(A)=0.4, P(B)=0.8$ and $P(B / A)=0.6$, then $P(A \cup B)$ is equal to

If $A$ and $B$ are two events and $A \neq \phi, B \neq \phi$, then

If $A$ and $B$ are events such that $P(A)=0.4, P(B)=0.3$ and $P(A \cup B)=0.5$, then $P\left(B^{\prime} \cap A\right)$ equals to

If $A$ and $B$ are two events such that $P(B)=\frac{3}{5}, P(A / B)=\frac{1}{2}$ and $P(A \cup B)=\frac{4}{5}$, then $P(A)$ equals to

In question 64 (above), $P\left(B / A^{\prime}\right)$ is equal to