Consider the following premises. t_2 or r_2. t -> ~q_4. t_2 <-> t. q_4. Can we infer r_2 from them?
 From t -> ~q_4, q_4 we can infer ~t. From t_2 <-> t, ~t we can infer ~t_2. Finally, from t_2 or r_2, ~t_2 we can infer r_2. Therefore, the answer is yes.