You can
put this solution on YOUR website! Note: I'm going to use '&' instead of '.'
1. ~S -> (~G v ~F)
2. (~F -> ~W) & W / :. S v ~G
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3. ~~S v (~G v ~F) 1 Material Implication
4. S v (~G v ~F) 3 Double Negation
5. (S v ~G) v ~F 4 Association
6. ~F v (S v ~G) 5 Commutation
7. F -> (S v ~G) 6 Material Implication
8. W & (~F -> ~W) 2 Commutation
9. W 8 Simplification
10. ~~W 9 Double Negation
11. ~F -> ~W 2 Simplification
12. ~~F 11,10 Modus Tollens
13. F 12 Double Negation
14. S v ~G 7,13 Modus Ponens