Consider the following premises. For all x_7, x_7 is a musician. For all x_7, x_7 is a musician if and only if x_7 is poor. There is at least one x_7 for which x_7 will take a plane. 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 will take a plane.
That is one of the premises. Therefore, the answer is yes.