What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Joseph is not a mechanic. If Richard were an office clerk, then Barbara is listening to a song. William is drinking water if and only if Richard is an office clerk. Barbara is listening to a song if and only if Joseph is a mechanic.
If William drinks water, then Richard is an office clerk. If Barbara listens to a song, then Joseph is a mechanic. If Richard were an office clerk, then William is drinking water. If Joseph were a mechanic, then Barbara is listening to a song. Barbara is not listening to a song.