Consider the following premises. S_7(a_7) -> r. forall x_7: W(x_7) <-> S_7(x_7). Can we infer W(a_7) -> r from them? If possible, name the inference rules being used at each step.
 From forall x_7: W(x_7) <-> S_7(x_7) we can infer W(a_7) <-> S_7(a_7) via universal instantiation. From W(a_7) <-> S_7(a_7) we can infer W(a_7) -> S_7(a_7) via biconditional elimination. Finally, from W(a_7) -> S_7(a_7), S_7(a_7) -> r we can infer W(a_7) -> r via transitivity. Therefore, the answer is yes.