Consider the following premises. w_4. p_4 -> r_2. t -> r_2. w_4 -> t. Can we infer r_2 from them?
 From w_4 we can infer w_4 or p_4. From w_4 -> t, t -> r_2 we can infer w_4 -> r_2. Finally, from w_4 -> r_2, p_4 -> r_2, w_4 or p_4 we can infer r_2. Therefore, the answer is yes.