What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Mary is not writing a letter. If Robert were an office clerk, then Jennifer is curious. If Jennifer were curious, then Linda is rich. If Linda were rich, then Mary is writing a letter. If Mary writes a letter, then Robert is an office clerk. John is listening to a song if and only if Robert is an office clerk.
Linda is not rich. If Robert were an office clerk, then Linda is rich. If Jennifer were curious, then Mary is writing a letter. If Linda were rich, then Robert is an office clerk. If Mary writes a letter, then Jennifer is curious. If John listens to a song, then Robert is an office clerk. If Robert were an office clerk, then John is listening to a song.