The simplified hole theory equation of state has been extended to polymer-solvent and polymer-polymer systems for the calculation of the P-V-T relations for five binary systems with good accuracy. Moreover, to test the equations proposed, the spinodal curves for two polymer-solvent systems have been estimated. Comparisons have been made between the calculated results of this work and the estimations from the well-recognized Simha and Somcynsky equation of state, which shows that the equations proposed are of the same quality as the latter, but much simpler in computation.