Consider the following premises. Barbara is sad. John is not driving a car. For all x_11, x_11 will work if and only if x_11 will drive a car. Can we infer the following from them? If we can, name the inference rule being used: Barbara is sad and John is not working.
 From the fact that for all x_11, x_11 will work if and only if x_11 will drive a car we can infer that John is working if and only if John is driving a car via universal instantiation. From the fact that John is working if and only if John is driving a car, and that John is not driving a car we can infer that John is not working via biconditional elimination. Finally, from the fact that Barbara is sad, and that John is not working we can infer that Barbara is sad and John is not working via conjunction. Therefore, the answer is yes.