1. N>~F
2. ~(XvV)
3. (~VvJ)>(C&F)
/~N
4. ~X&~V 2, DeMorgan
5. ~V&~X 4, Commutation
6. ~V 5, Simplification
7. ~(~VvJ)v(C&F) 3, Material Implication
8. (~~V&~J)v(C&F) 7, DeMorgan
9. (V&~J)v(C&F) 8, Double negation
10. [Vv(C&F)]&[~Jv(C&F)] 9, Distribution
11. [~~Vv(C&F)]&[~Jv(C&F)] 10, Double negation
12. [~V>(C&F)]&[~Jv(C&F)] 11, Material Implication
13. ~V>(C&F) 12, Simplification
14. C&F 13,6, Modus ponens
15. F 14, simplification
16. ~~F>~N 1, transposition
17. F>~N 16, Double negation
18. ~N 17,15, Modus ponens
Edwn