The vapour pressure of pure liquids $$A$$ and $$B$$ are 450 and $$700 \mathrm{~mm}$$ of $$\mathrm{Hg}$$ at $$350 \mathrm{~K}$$ respectively. If the total vapour pressure of the mixture is $$600 \mathrm{~mm}$$ of $$\mathrm{Hg}$$, the composition of the mixture in the solution is