What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If Susan were curious, then it is overcast. If it is overcast, then Charles is driving a car. If Charles drives a car, then it is overcast.
If Susan were curious, then Charles is driving a car. It is overcast if and only if Charles is driving a car. Charles is driving a car if and only if it is overcast.