Consider the following premises. For all x_4, if x_4 were a writer, then x_4 is driving a car. For all x_4, if x_4 were a nurse, then x_4 is a writer. For all x_4, if x_4 drives a car, then x_4 is a nurse. Can we infer the following from them? If we can, name the inference rule being used: If Robert were a nurse, then Robert is driving a car.
 From the fact that for all x_4, if x_4 were a nurse, then x_4 is a writer, and that for all x_4, if x_4 were a writer, then x_4 is driving a car we can infer that for all x_4, if x_4 were a nurse, then x_4 is driving a car via universal transitivity. From the fact that for all x_4, if x_4 were a nurse, then x_4 is driving a car, and that for all x_4, if x_4 drives a car, then x_4 is a nurse we can infer that for all x_4, x_4 is a nurse if and only if x_4 will drive a car via universal biconditional introduction. From the fact that for all x_4, x_4 is a nurse if and only if x_4 will drive a car we can infer that Robert is a nurse if and only if Robert is driving a car via universal instantiation. Finally, from the fact that Robert is a nurse if and only if Robert is driving a car we can infer that if Robert were a nurse, then Robert is driving a car via biconditional elimination. Therefore, the answer is yes.