Consider the following premises. For all z, if z were a scientist, then z is poor. For all z, z is not an electrician. For all z, z is poor if and only if z is a scientist. For all z, z is poor if and only if z is an electrician. Can we infer the following from them? If we can, name the inference rule being used: For all z, z is not a scientist.
 From the fact that for all z, z is poor if and only if z is an electrician, and that for all z, z is not an electrician we can infer that for all z, z is not poor via universal biconditional elimination. From the fact that for all z, z is poor if and only if z is a scientist we can infer that for all z, if z were poor, then z is a scientist via universal biconditional elimination. From the fact that for all z, if z were a scientist, then z is poor, and that for all z, if z were poor, then z is a scientist we can infer that for all z, z is a scientist if and only if z is poor via universal biconditional introduction. From the fact that for all z, z is a scientist if and only if z is poor we can infer that for all z, if z were a scientist, then z is poor via universal biconditional elimination. Finally, from the fact that for all z, if z were a scientist, then z is poor, and that for all z, z is not poor we can infer that for all z, z is not a scientist via universal modus tollens. Therefore, the answer is yes.