Determining molar enthalpy of vapourization from a graph?

[PoochGroup]

 

I know the formula for ln{k2/k1}=Ea/R {1/T1 - 1/T2}, but I am confused as to how to apply it to this graph. I believe T can be found by taking two points from the graph such as at 5 and 1 on the X axis then inverting the value to obtain T in kelvins. But how do I work with Ln P?

 

Thanks.