Consider the following premises. w_2 -> t. w_2 -> r_1. r_1 -> w_2. Can we infer r_1 -> t from them? If possible, name the inference rules being used at each step.
 From w_2 -> r_1, r_1 -> w_2 we can infer w_2 <-> r_1 via biconditional introduction. From w_2 <-> r_1 we can infer r_1 -> w_2 via biconditional elimination. Finally, from r_1 -> w_2, w_2 -> t we can infer r_1 -> t via transitivity. Therefore, the answer is yes.