An azeotrope consists of \(42.0 \mathrm{~mol}\) per cent acetone (1) and \(58.0 \mathrm{~mol}\) per cent methanol at \(760 \mathrm{~mm} \mathrm{Hg}\) and \(313 \mathrm{~K}\). At \(313 \mathrm{~K}\), the vapour pressure of acetone and methanol are \(786 \mathrm{~mm} \mathrm{Hg}\) and \(551 \mathrm{~mm} \mathrm{Hg}\) respectively. Calculate the van Laar constants.