What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z_1, if z_1 were poor, then z_1 is taking a plane. For all z_1, z_1 will take a plane if and only if z_1 is poor.
For all z_1, if z_1 takes a plane, then z_1 is poor. For all z_1, if z_1 were poor, then z_1 is taking a plane.