Question 1029890
1. ~N ⊃ (~R ⊃ C)  -------------------Hypothesis
2. (~N &~R) ⊃ C) --------------------exportation
3. ~(N vR)  ⊃ C   -------------------de Morgan's law
4. ~C ⊃(N vR)     -------------------Contrapositive of #3
5. ~C                    --------------------Hypothesis
6. N v R               ---------------------modus ponens on #4 and #5
7. R ⊃ N         ---------------------Hypothesis
8. ~R v N       ----------------------material implication
9. (N v R) & (N v ~R) ----------------Commutativity on #8, and conjunction on #6 and #8
10. N v ( R & ~R) -------------------distributivity
11.  N v F       ---------------------negation law
12. N             ---------------------Identity Law