For any two events A and B, if P (Ā)=1/2, P (B̄)=2/3 and P ( A ∩ B )=1/4, then P ((Ā)/(B̄)) equals:

For any two events A and B , if $\displaystyle \mathrm{P}(\overline{\mathrm{A}})=\frac{1}{2}, \mathrm{P}(\overline{\mathrm{B}})=\frac{2}{3}$ and $\displaystyle \mathrm{P}(\mathrm{A} \cap \mathrm{B})=\frac{1}{4}$, then $\displaystyle \mathrm{P}\left(\frac{\overline{\mathrm{A}}}{\overline{\mathrm{B}}}\right)$ equals :