Consider the following premises. u_1 or ~t. q -> u_1. r or t. r -> q. Can we infer u_1 from them?
 From r -> q, q -> u_1 we can infer r -> u_1. From u_1 or ~t we can infer t -> u_1. Finally, from r -> u_1, t -> u_1, r or t we can infer u_1. Therefore, the answer is yes.