Consider the following premises. For all x_3, x_3 is a bartender if and only if x_3 is sad. For all x_3, x_3 is a bartender. Can we infer the following from them? For all x_3, x_3 is sad.
 From the fact that for all x_3, x_3 is a bartender if and only if x_3 is sad we can infer that for all x_3, if x_3 were a bartender, then x_3 is sad. Finally, from the fact that for all x_3, if x_3 were a bartender, then x_3 is sad, and that for all x_3, x_3 is a bartender we can infer that for all x_3, x_3 is sad. Therefore, the answer is yes.