Consider the following premises. t -> q_7. u_1 <-> q_7. ~u_1. Can we infer ~t from them? If possible, name the inference rules being used at each step.
 From u_1 <-> q_7, ~u_1 we can infer ~q_7 via biconditional elimination. Finally, from t -> q_7, ~q_7 we can infer ~t via modus tollens. Therefore, the answer is yes.