Consider the following premises. u. ~q_21. u -> p_2. p_21 <-> q_21. Can we infer p_2 and ~p_21 from them?
 From p_21 <-> q_21 we can infer p_21 -> q_21. From u -> p_2, u we can infer p_2. From p_21 -> q_21, ~q_21 we can infer ~p_21. Finally, from p_2, ~p_21 we can infer p_2 and ~p_21. Therefore, the answer is yes.