What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is not rich. For all x_7, x_7 is a bartender if and only if x_7 is sad. It is late if and only if David is rich. It is late if and only if Sarah is sad.
If it is late, then David is rich. If it is late, then Sarah is sad. If David were rich, then it is late. If Sarah were sad, then it is late. It is not late. For all x_7, if x_7 were a bartender, then x_7 is sad. For all x_7, if x_7 were sad, then x_7 is a bartender.