Consider the following premises. If Linda were a mechanic, then it is cloudy. If it is cloudy, then Susan is a writer. If Susan were a writer, then it is raining. If it rains, then Linda is a mechanic. Can we infer the following from them? If we can, name the inference rule being used: Linda is a mechanic if and only if it is cloudy.
 From the fact that if Susan were a writer, then it is raining, and that if it rains, then Linda is a mechanic we can infer that if Susan were a writer, then Linda is a mechanic via transitivity. From the fact that if it is cloudy, then Susan is a writer, and that if Susan were a writer, then Linda is a mechanic we can infer that if it is cloudy, then Linda is a mechanic via transitivity. Finally, from the fact that if Linda were a mechanic, then it is cloudy, and that if it is cloudy, then Linda is a mechanic we can infer that Linda is a mechanic if and only if it is cloudy via biconditional introduction. Therefore, the answer is yes.