Consider the following premises. Sarah is not a musician. If Sarah were a musician, then it is sunny. If it is sunny, then Sarah is a musician. Can we infer the following from them? If we can, name the inference rule being used: It is sunny.
 From the fact that if it is sunny, then Sarah is a musician, and that if Sarah were a musician, then it is sunny we can infer that it is sunny if and only if Sarah is a musician via biconditional introduction. Finally, from the fact that it is sunny if and only if Sarah is a musician, and that Sarah is not a musician we can infer that it is not sunny via biconditional elimination, which contradicts that It is sunny. Therefore, the answer is no.