Consider the following premises. For all x_16, x_16 will cook if and only if x_16 is sad. For all x_16, x_16 will cook. Can we infer the following from them? If we can, name the inference rule being used: Thomas is sad or it is sunny.
 From the fact that for all x_16, x_16 will cook if and only if x_16 is sad we can infer that for all x_16, if x_16 cooks, then x_16 is sad via universal biconditional elimination. From the fact that for all x_16, if x_16 cooks, then x_16 is sad, and that for all x_16, x_16 will cook we can infer that for all x_16, x_16 is sad via universal modus ponens. From the fact that for all x_16, x_16 is sad we can infer that Thomas is sad via universal instantiation. Finally, from the fact that Thomas is sad we can infer that Thomas is sad or it is sunny via addition. Therefore, the answer is yes.