Consider the following premises. It is not cold. Sarah is sad or it is not overcast. It is cold if and only if Sarah is sad. Can we infer the following from them? If we can, name the inference rule being used: It is overcast.
 From the fact that Sarah is sad or it is not overcast we can infer that if it is overcast, then Sarah is sad via rewriting. From the fact that it is cold if and only if Sarah is sad, and that it is not cold we can infer that Sarah is not sad via biconditional elimination. Finally, from the fact that if it is overcast, then Sarah is sad, and that Sarah is not sad we can infer that it is not overcast via modus tollens, which contradicts that It is overcast. Therefore, the answer is no.