1. M&~Q 2. M->S 3. S->P /~(P->Q) 4. M 1, siomplification 5. S 2,4, modus ponens 6. P 3,5, modus ponens 7. ~Q&M 1, commutation 8. ~Q 7, simplification 9. P&~Q 6,8, conjunction of premises 10. ~~P&Q 9, double negation 11. ~(~PvQ) 10, DeMorgan's law 12. ~(P->Q) 11, Material implication Edwin