Consider the following premises. w or r_2. q_1. w -> q_2. q_2 <-> r_2. Can we infer q_2 from them? If possible, name the inference rules being used at each step.
 From q_2 <-> r_2 we can infer r_2 -> q_2 via biconditional elimination. Finally, from w -> q_2, r_2 -> q_2, w or r_2 we can infer q_2 via disjunction elimination. Therefore, the answer is yes.