= (? p∨q)-& gt； (q ∨ r) (implied eternal truth)
= (p∧？ Q)∨(q ∨ r) (implied eternal truth, De Morgan's law)
= (p∨ q ∨ r) ∧(？ Q ∨ q ∨ r) (distribution law)
= (p∨ q ∨ r) ∧True
=(p∨ q ∨ r)