Consider the following premises. For all x_7, if x_7 were a lawyer, then x_7 is a writer. There is at least one x_7 for which x_7 is a lawyer if and only if x_7 is a writer. Can we infer the following from them? There is at least one x_7 for which if x_7 were a writer, then x_7 is a lawyer.
Yes.