Consider the following premises. p_1 -> r. r_2 or u. ~r_2 or p_1. u -> r. s_4 and p_2. Can we infer s_4 and r from them?
 From r_2 or u, ~r_2 or p_1 we can infer u or p_1. From s_4 and p_2 we can infer s_4. From u -> r, p_1 -> r, u or p_1 we can infer r. Finally, from s_4, r we can infer s_4 and r. Therefore, the answer is yes.