Consider the following premises. forall x_9: P_9(x_9) <-> Q_9(x_9). P_9(i) -> q. Can we infer Q_9(i) -> q from them? If possible, name the inference rules being used at each step.
 From forall x_9: P_9(x_9) <-> Q_9(x_9) we can infer forall x_9: Q_9(x_9) -> P_9(x_9) via universal biconditional elimination. From forall x_9: Q_9(x_9) -> P_9(x_9) we can infer Q_9(i) -> P_9(i) via universal instantiation. Finally, from Q_9(i) -> P_9(i), P_9(i) -> q we can infer Q_9(i) -> q via transitivity. Therefore, the answer is yes.