Consider the following premises. t_2 <-> q_4. ~t_2. Can we infer ~q_4 from them? If possible, name the inference rules being used at each step.
 From t_2 <-> q_4 we can infer q_4 -> t_2 via biconditional elimination. Finally, from q_4 -> t_2, ~t_2 we can infer ~q_4 via modus tollens. Therefore, the answer is yes.