Consider the following premises. Karen is a mechanic if and only if Charles is working. If Karen were not a mechanic, then Susan is a sailor. Charles is not working. Can we infer the following from them? Susan is a sailor or John is sleeping.
 From the fact that Karen is a mechanic if and only if Charles is working, and that Charles is not working we can infer that Karen is not a mechanic. From the fact that if Karen were not a mechanic, then Susan is a sailor, and that Karen is not a mechanic we can infer that Susan is a sailor. Finally, from the fact that Susan is a sailor we can infer that Susan is a sailor or John is sleeping. Therefore, the answer is yes.