The vapour pressures of two volatile liquids \( A \) and \( B \) at \( 25^\circ \text{C} \) are \( 50 \, \text{Torr} \) and \( 100 \, \text{Torr} \), respectively. If the liquid mixture contains \( 0.3 \) mole fraction of \( A \), then the mole fraction of liquid \( B \) in the vapour phase is \( \frac{x}{17} \). The value of \( x \) is ______.