vapor pressure Questions

At $80^{\circ }\text{C}$, the vapour pressure of pure liquid ‘A’ is $520\text{mm Hg}$ and that of pure liquid ‘B’ is $1000\text{mm Hg}$. If a mixture solution of ‘A’ and ‘B’ boils at $80^{\circ }\text{C}$ and $1\text{atm}$ pressure, the amount of ‘A’ in the mixture is ($1\text{atm}=760\text{mm Hg}$):