Consider the following premises. q -> p. p_9 -> q. p_9 <-> q_9. Can we infer q_9 -> p from them?
 From p_9 <-> q_9 we can infer q_9 -> p_9. From q_9 -> p_9, p_9 -> q we can infer q_9 -> q. Finally, from q_9 -> q, q -> p we can infer q_9 -> p. Therefore, the answer is yes.