Consider the following premises. For all z_1, z_1 will take a plane if and only if z_1 is poor. For all z_1, z_1 will take a plane and z_1 is a scientist. Can we infer the following from them? If we can, name the inference rule being used: For all z_1, z_1 is poor.
 From the fact that for all z_1, z_1 will take a plane and z_1 is a scientist we can infer that for all z_1, z_1 will take a plane via universal simplification. From the fact that for all z_1, z_1 will take a plane if and only if z_1 is poor we can infer that for all z_1, if z_1 takes a plane, then z_1 is poor via universal biconditional elimination. Finally, from the fact that for all z_1, if z_1 takes a plane, then z_1 is poor, and that for all z_1, z_1 will take a plane we can infer that for all z_1, z_1 is poor via universal modus ponens. Therefore, the answer is yes.