Consider the following premises. For all x_8, x_8 is a musician if and only if x_8 is a nurse. For all x_8, if x_8 were a musician, then x_8 is a taxi driver. For all x_8, if x_8 were a taxi driver, then x_8 is a nurse. Can we infer the following from them? If we can, name the inference rule being used: If John were a nurse, then John is a musician.
 From the fact that for all x_8, if x_8 were a musician, then x_8 is a taxi driver, and that for all x_8, if x_8 were a taxi driver, then x_8 is a nurse we can infer that for all x_8, if x_8 were a musician, then x_8 is a nurse via universal transitivity. From the fact that for all x_8, x_8 is a musician if and only if x_8 is a nurse we can infer that for all x_8, if x_8 were a nurse, then x_8 is a musician via universal biconditional elimination. From the fact that for all x_8, if x_8 were a musician, then x_8 is a nurse, and that for all x_8, if x_8 were a nurse, then x_8 is a musician we can infer that for all x_8, x_8 is a musician if and only if x_8 is a nurse via universal biconditional introduction. From the fact that for all x_8, x_8 is a musician if and only if x_8 is a nurse we can infer that John is a musician if and only if John is a nurse via universal instantiation. Finally, from the fact that John is a musician if and only if John is a nurse we can infer that if John were a nurse, then John is a musician via biconditional elimination. Therefore, the answer is yes.