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