4. A simplification,2 5. B⊃C modus ponens,1,4 6. ~C⊃~B contrapositive,5 7. ~C simplification,2 8. ~B modus ponens,6,7 9. ~B v D disjunctive addition,8 10 ~(A&E) modus ponens,3,9 11. ~Av~E Demorgan's,10 12. ~~A double negation,4 13. ~E disjunctive syllogism,11,12 14. ~C&~E conjunction,7,13 15. ~(CvE) Demorgan's,14 Edwin