What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Robert were a bartender, then Susan is making tea. If James writes a letter, then Susan is making tea. If Robert were a bartender, then James is writing a letter. If Susan makes tea, then Robert is a bartender.
If James writes a letter, then Robert is a bartender. If Robert were a bartender, then Susan is making tea. If Susan makes tea, then James is writing a letter. Robert is a bartender if and only if Susan is making tea. Susan is making tea if and only if Robert is a bartender.