Consider the following premises. For all x_18, x_18 will make tea. For all x_18, x_18 will make tea if and only if x_18 will work. For all x_18, if x_18 were a doctor, then x_18 is working. Can we infer the following from them? If we can, name the inference rule being used: James is working or Robert is running.
 From the fact that for all x_18, x_18 will make tea if and only if x_18 will work we can infer that for all x_18, if x_18 makes tea, then x_18 is working via universal biconditional elimination. From the fact that for all x_18, x_18 will make tea we can infer that for all x_18, x_18 will make tea or x_18 is a doctor via universal addition. From the fact that for all x_18, if x_18 makes tea, then x_18 is working, that for all x_18, if x_18 were a doctor, then x_18 is working, and that for all x_18, x_18 will make tea or x_18 is a doctor we can infer that for all x_18, x_18 will work via universal disjunction elimination. From the fact that for all x_18, x_18 will work we can infer that James is working via universal instantiation. Finally, from the fact that James is working we can infer that James is working or Robert is running via addition. Therefore, the answer is yes.