Consider the following premises. p_7 <-> r. p_7 or ~u_2. u_2 or r. Can we infer p_7 from them?
 From p_7 or ~u_2 we can infer u_2 -> p_7. From p_7 <-> r we can infer r -> p_7. Finally, from u_2 -> p_7, r -> p_7, u_2 or r we can infer p_7. Therefore, the answer is yes.