1. A -> ~(B -> G) 2. A v G / A <-> ~G ----------------------- 3. ~A v ~(B -> G) 1 Material Implication 4. ~A v ~(~B v G) 3 Material Implication 5. ~A v (~~B & ~G) 4 DeMorgan's Theorem 6. ~A v (B & ~G) 5 Double Negation 7. (~A v B) & (~A v ~G) 6 Distribution 8. (~A v ~G) & (~A v B) 7 Commutation 9. ~A v ~G 8 Simplification 10. A -> ~G 9 Material Implication 11. G v A 2 Commutation 12. ~~G v A 11 Double Negation 13. ~G -> A 12 Material Implication 14. (A -> ~G) & (~G -> A) 10,13 Conjunction 15. A <-> ~G 14 Material Equivalence