What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If David plays squash, then Barbara is rich. Susan is a police officer if and only if Barbara is rich. If John were a poet, then David is playing squash. If Susan were a police officer, then John is a poet.
If John were a poet, then Barbara is rich. If Susan were a police officer, then David is playing squash. If Susan were a police officer, then Barbara is rich. If Barbara were rich, then Susan is a police officer.