Consider the following premises. t -> q_9. w <-> q_9. s -> t. Can we infer s -> w from them? If possible, name the inference rules being used at each step.
 From w <-> q_9 we can infer q_9 -> w via biconditional elimination. From s -> t, t -> q_9 we can infer s -> q_9 via transitivity. Finally, from s -> q_9, q_9 -> w we can infer s -> w via transitivity. Therefore, the answer is yes.