Given the following information:

C(s) à C(g), H = +715 kJmol-1
Cl2(g) à 2Cl(g), H = +242 kJmol-1
C(s) + 2Cl2(g) à CCl4(g), H = -135.5 kJmol-1
Calculate the average bond dissociation enthalpy of a C-Cl bond.