Components $A$ and $B$ form an azeotrope. The saturation vapour pressures of $A$ and $B$ at the boiling temperature of the azeotrope are $87 \: \mathrm{kPa}$ and $72.7 \: \mathrm{kPa}$, respectively. The azeotrope composition is $\_\_\_\_\_\_ \: \mathrm{mol} \% \: A$ (rounded off to the nearest integer).
GIVEN:
$$ \ln \frac{\gamma_{A}}{\gamma_{B}}=0.9\left(x_{B}^{2}-x_{A}^{2}\right)$$
where $x_{i}$ and $\gamma_{i}$ are the liquid phase mole fraction and activity coefficient of component $i$, respectively.
