If $\mathrm{P}(\mathrm{A})=\frac{2}{5}, \mathrm{P}(\mathrm{B})=\frac{3}{10}$ and $\mathrm{P}(\mathrm{A} \cap \mathrm{B})=\frac{1}{5}$, then $\mathrm{P}\left(\mathrm{A}^{\prime} \mid \mathrm{B}^{\prime}\right) . \mathrm{P}\left(\mathrm{B}^{\prime} \mid \mathrm{A}^{\prime}\right)$ is equal to