proposition: Lemma Zdivides_mult_lr : forall a b c d : Z, (a * b)%Z = (d * c)%Z -> a <> 0%Z -> Zdivides a c -> Zdivides d b.
proof: Proof. intros a b c d; rewrite (Zmult_comm d c); apply Zdivides_mult_ll. Qed.
imports: CoRN.model.Zmod.ZBasics