1.S>(R&~T) 2.(S&R)>(TvE) 3.(Qv~T)>~E /~S |4. ~~S Assumption for indirect proof |5. S 4, double negation |6. R&~T 1,5, modus ponens |7. R 6, simplification |8. ~T&R 6, commutativity |9. ~T 8, simplification |10. S&R 5,6, conjunction |11. TvE 2,10, modus ponens |12. E 11,9, disjunctive syllogism |13. ~~E 12, double negation |14. ~(Qv~T) 3,13 modus tollens |15. ~Q&~~T 14, deMorgan's law |16. ~Q&T 15, double negation |17. T&~Q 16, commutation |18. T 17, simplification |19. T&~T 18,9, conjunction 20. ~S lines 4-19 indirect proof Edwin