Consider the following premises. r_2 or ~u_2. p_7 or ~r_2. Can we infer u_2 -> p_7 from them? If possible, name the inference rules being used at each step.
 From p_7 or ~r_2 we can infer r_2 -> p_7 via rewriting. From r_2 or ~u_2 we can infer u_2 -> r_2 via rewriting. Finally, from u_2 -> r_2, r_2 -> p_7 we can infer u_2 -> p_7 via transitivity. Therefore, the answer is yes.