At 300 K, the vapour pressure of a solution containing 1 mole of n-hexane and 3 moles of n-heptane is 550 mm of Hg. At the same temperature, if one…

At $\displaystyle 300$ K , the vapour pressure of a solution containing $\displaystyle 1$ mole of n-hexane and $\displaystyle 3$ moles of n-heptane is $\displaystyle 550$ mm of Hg. At the same temperature, if one more mole of n-heptane is added to this solution, the vapour pressure of the solution increases by $\displaystyle 10$ mm of Hg. What is the vapour pressure in mm Hg of n-heptane in its pure state \_\_\_\_?