Consider the following premises. t -> w. q_8 -> t. u <-> q_8. Can we infer u -> w from them? If possible, name the inference rules being used at each step.
 From u <-> q_8 we can infer u -> q_8 via biconditional elimination. From q_8 -> t, t -> w we can infer q_8 -> w via transitivity. Finally, from u -> q_8, q_8 -> w we can infer u -> w via transitivity. Therefore, the answer is yes.