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