Consider the following premises. If it rains, then Sarah is taking a plane. It is raining if and only if Sarah is taking a plane. It is raining or Sarah is not taking a plane. Can we infer the following from them? Sarah is taking a plane if and only if it is raining.
 From the fact that it is raining or Sarah is not taking a plane we can infer that if Sarah takes a plane, then it is raining. Finally, from the fact that if Sarah takes a plane, then it is raining, and that if it rains, then Sarah is taking a plane we can infer that Sarah is taking a plane if and only if it is raining. Therefore, the answer is yes.