Don't skip a space just after "(" or "[" and don't skip a space just before ")" or "]". It looks confusing when you do. Since by exportation the conclusion P ⊃ (M ⊃ W) is equivalent to (P • M) ⊃ W, we will assume P • M for a conditional proof 1. P ⊃ [(L v M) ⊃ (N • O)] 2. (O v T) ⊃ W / P ⊃ (M ⊃ W), same as (P • M) ⊃ W |3. P • M ACP |4. P 3, Simplification |5. (L v M) ⊃ (N • O) 1,4, Modus ponens |6. M • P 3, Commutation |7. M 6, Simplification |8. M v L 7, Addition |9. L v M 8, Commutation |10. N • O 5,9 Modus ponens |11. O • N 10, Commutation |12. O 11, Simplification |13. O v T 12, Addition |14. W 2,13, Modus ponens 15. (P • M) ⊃ W lines 3-14 Conditional proof. 16. P ⊃ (M ⊃ W) 15, Exportation Edwin