Consider the following premises. If David were a server, then Sarah is playing a game. Linda is a doctor. If Sarah plays a game, then David is a server. David is a server. Can we infer the following from them? If we can, name the inference rule being used: Sarah is playing a game.
 From the fact that David is a server, and that Linda is a doctor we can infer that David is a server and Linda is a doctor via conjunction. From the fact that if Sarah plays a game, then David is a server, and that if David were a server, then Sarah is playing a game we can infer that Sarah is playing a game if and only if David is a server via biconditional introduction. From the fact that David is a server and Linda is a doctor we can infer that David is a server via simplification. From the fact that Sarah is playing a game if and only if David is a server we can infer that if David were a server, then Sarah is playing a game via biconditional elimination. Finally, from the fact that if David were a server, then Sarah is playing a game, and that David is a server we can infer that Sarah is playing a game via modus ponens. Therefore, the answer is yes.