Trying to justify each step correctly in proof sequence

Question

I am trying Justify each step in the proof sequence below for correctly with [A → (B ∨ C)] ∧ B' ∧ C' → A'

So I justified my steps here but I am not sure at 1 to 3 if I did it correctly.

1. A → (B ∨ C) = Conjunctive simplification
2. B′ = Conjunctive Simplification
3. C′ = Conjunctive Simplification
4. B′∧ C′ = Conjunctive Addition
5. (B ∨ C)′ = DeMorgan's Law
6. A′ = Contrapositive