Chemistry problem ???????????????

Question

The dissociaton energy of CH4 & C2H6 are respectively 360,620 Kcal/mol.The bond energy of C-C bond is-------

Answer 1

I hope this is right

CH4:

bond energy of C-H is 360/4 = 90 Kcal/mol

C2H6:

total bond energy of C-H is 90*6 = 540 Kcal/mol

therefore bond energy of C-C is 620-540 = 80 Kcal/mol