Chapter 12, Problem 19PE

At $\text{20}\text{.0 °C}$, the vapor pressure of cyclohexane, a nonpolar hydrocarbon, is 66.9 torr and that of toluene, a hydrocarbon related to benzene, is 21.1 torr. What is the vapor pressure of a solution of the two at $\text{20}\text{.0 °C}$ when toluene is present at a mole fraction of 0.250? (Hint: Recall that all mole fractions of the components of a mixture must add up to 1.00.)