1. P-> (~Q&R) 2. (Qv~R) ->S 3. ~SvP Conclusion: ~Q 4. (~~Qv~R) -> S 2,DN (double negation) 5. ~(~Q&R) -> S 4,DM (deMorgan's law) 6. ~S -> ~~(~Q&R) 5,CP (contrapositive) 7. ~S -> (~Q&R) 6,DN (double negation) 8. ~Q&R 7,1,3,CD (constructive dilemma) 9. ~Q 8,simp. (simplification of a conjunction) Edwin