Consider the following premises. t -> p. p_1 -> p. p_1. Can we infer p from them? If possible, name the inference rules being used at each step.
 From p_1 we can infer p_1 or t via addition. Finally, from p_1 -> p, t -> p, p_1 or t we can infer p via disjunction elimination. Therefore, the answer is yes.