Consider the following premises. For all x_3, x_3 is rich if and only if x_3 is a lawyer. For all x_3, x_3 is rich. Can we infer the following from them? There is at least one x_3 for which x_3 is not a lawyer.
 From the fact that for all x_3, x_3 is rich if and only if x_3 is a lawyer we can infer that for all x_3, if x_3 were rich, then x_3 is a lawyer. Finally, from the fact that for all x_3, if x_3 were rich, then x_3 is a lawyer, and that for all x_3, x_3 is rich we can infer that for all x_3, x_3 is a lawyer, which contradicts that There is at least one x_3 for which x_3 is not a lawyer. Therefore, the answer is no.