Consider the following premises. For all x_4, if x_4 were happy, then x_4 is making tea. For all x_4, if x_4 were bored, then x_4 is happy. For all x_4, if x_4 makes tea, then x_4 is bored. Can we infer the following from them? If we can, name the inference rule being used: If Robert makes tea, then Robert is happy.
 From the fact that for all x_4, if x_4 makes tea, then x_4 is bored, and that for all x_4, if x_4 were bored, then x_4 is happy we can infer that for all x_4, if x_4 makes tea, then x_4 is happy via universal transitivity. From the fact that for all x_4, if x_4 were happy, then x_4 is making tea, and that for all x_4, if x_4 makes tea, then x_4 is happy we can infer that for all x_4, x_4 is happy if and only if x_4 will make tea via universal biconditional introduction. From the fact that for all x_4, x_4 is happy if and only if x_4 will make tea we can infer that Robert is happy if and only if Robert is making tea via universal instantiation. Finally, from the fact that Robert is happy if and only if Robert is making tea we can infer that if Robert makes tea, then Robert is happy via biconditional elimination. Therefore, the answer is yes.