What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? It is not overcast. If it is overcast, then Susan is a mechanic. If Susan were not a mechanic, then Thomas is playing a game. If Susan were a mechanic, then it is overcast.
Susan is not a mechanic. It is overcast if and only if Susan is a mechanic. Susan is a mechanic if and only if it is overcast.