Ln(P2/P1) = (DH/R)*(1/T1-1/T2) . . . . . .(1)
where DH reads Delta H, and is the Hvap you are looking for when P1=100,
P2=760, T1=278.6, and T2=330. Put in every thing we get:
Hvap = R*Ln(P2/P1)/(1/T1-1/T2)
= 8.314*Ln(760/100)/(1/278.6-1/330)
= 30.2 (kJ/mol)