Consider the following premises. If it rains, then it is cloudy. It is raining if and only if it is sunny. If it is cloudy, then it is sunny. Can we infer the following from them? If is not true that it is sunny if and only if it is raining.
 From the fact that it is raining if and only if it is sunny we can infer that if it is sunny, then it is raining. From the fact that if it rains, then it is cloudy, and that if it is cloudy, then it is sunny we can infer that if it rains, then it is sunny. Finally, from the fact that if it is sunny, then it is raining, and that if it rains, then it is sunny we can infer that it is sunny if and only if it is raining, which contradicts that If is not true that it is sunny if and only if it is raining. Therefore, the answer is no.