Consider the following premises. p_8 <-> q_8. ~p_8. q_8 <-> t. r_3 <-> t. Can we infer ~r_3 from them? If possible, name the inference rules being used at each step.
 From p_8 <-> q_8, ~p_8 we can infer ~q_8 via biconditional elimination. From q_8 <-> t, ~q_8 we can infer ~t via biconditional elimination. Finally, from r_3 <-> t, ~t we can infer ~r_3 via biconditional elimination. Therefore, the answer is yes.