What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_1, x_1 is sad if and only if x_1 is poor. Barbara is not poor.
For all x_1, if x_1 were sad, then x_1 is poor. For all x_1, if x_1 were poor, then x_1 is sad.