Consider the following premises. For all x_6, if x_6 works, then x_6 is a police officer. For all x_6, x_6 is a police officer if and only if x_6 will work. Can we infer the following from them? If we can, name the inference rule being used: If Jessica were a police officer, then Jessica is working.
 From the fact that for all x_6, x_6 is a police officer if and only if x_6 will work we can infer that for all x_6, if x_6 were a police officer, then x_6 is working via universal biconditional elimination. From the fact that for all x_6, if x_6 works, then x_6 is a police officer, and that for all x_6, if x_6 were a police officer, then x_6 is working we can infer that for all x_6, x_6 will work if and only if x_6 is a police officer via universal biconditional introduction. From the fact that for all x_6, x_6 will work if and only if x_6 is a police officer we can infer that Jessica is working if and only if Jessica is a police officer via universal instantiation. Finally, from the fact that Jessica is working if and only if Jessica is a police officer we can infer that if Jessica were a police officer, then Jessica is working via biconditional elimination. Therefore, the answer is yes.