Each of the following exercises presents a flawless formal proof of validity for the indicated argument. For each proof, state the justification for each inferred statement (i.e., each statement that is not a premise).

1. (L ⊃ M) ⊃ (N ≡ O)
2. (P ⊃ ~ Q) ⊃ (M ≡ ~ Q)
3. {[(P ⊃ ~ Q) ꓦ (R ≡ S)]⋅
(N ꓦ O)} ⊃ [(R ≡ S) ⊃ (L ⊃ M)]
4. (P ⊃ ~ Q)  (R ≡ S)
5. N ꓦ O
∴ (M ≡ ~ Q) ꓦ (N ≡ O)
6. [(P ⊃ ~ Q) ꓦ (R ≡ S)] ⋅ (N ꓦ O)
7. (R ≡ S) ⊃ (L ⊃ M)
8. (R ≡ S) ⊃ (N ≡ O)
9. [(P ⊃ ~ Q) ⊃ (M ≡ ~ Q)]⋅
[(R ≡ S) ⊃ (N ≡ O)]
10. (M ≡ ~ Q) ꓦ (N ≡ O)