Consider the following premises. u_3 <-> t. p_3 -> t. u_3 -> p_3. Can we infer t -> p_3 from them? If possible, name the inference rules being used at each step.
 From u_3 <-> t we can infer t -> u_3 via biconditional elimination. Finally, from t -> u_3, u_3 -> p_3 we can infer t -> p_3 via transitivity. Therefore, the answer is yes.