What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? There is at least one x for which if x were a cashier, then x is poor. For all x, x is poor if and only if x will climb a mountain. For all x, x is a cashier. For all x, x will not climb a mountain. For all x, if x writes a letter, then x is not a musician.
Since the premises are contradictory, we can infer anything from them.