1. ~N ⊃ (~R ⊃ C) 2. R ⊃ N 3. ~C /N 4. (~N ● ~R) ⊃ C 1, Importation 5. ~C ⊃ ~(~N ● ~R) 4, Transposition 6. ~C ⊃ (~~N v ~~R) 5, DeMorgan's law 7. ~C ⊃ (N v R) 6, Double Negation 8. N v R 7,3, Modus Ponens 9. R v N 8, Commutation 10. ~~R v N 9, Double Negation 11. ~R ⊃ N 10, Material Implication 12. R v ~R Tautology 13. N v N 2,11,12, Constructive Dilemma 14. N 13, Tautology Edwin