Consider the following premises. t_4. t_4 <-> r_3. q_1 -> r_3. Can we infer r_3 from them?
 From t_4 <-> r_3 we can infer t_4 -> r_3. From t_4 we can infer t_4 or q_1. Finally, from t_4 -> r_3, q_1 -> r_3, t_4 or q_1 we can infer r_3. Therefore, the answer is yes.