Consider the following premises. For all x_7, if x_7 were a janitor, then x_7 is poor. For all x_7, x_7 is not poor. For all x_7, x_7 is a janitor and x_7 will climb a mountain. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_7 for which x_7 is not fast.
The premises are contradictory and we can infer anything from them. Therefore, the answer is yes.