Consider the following premises. For all x_8, x_8 will take a plane or x_8 is an astronaut. For all x_8, x_8 is a mechanic or x_8 is not an astronaut. There is at least one x_8 for which x_8 will take a plane if and only if x_8 is a mechanic. Can we infer the following from them? There is at least one x_8 for which x_8 is a mechanic.
 From the fact that there is at least one x_8 for which x_8 will take a plane if and only if x_8 is a mechanic we can infer that there is at least one x_8 for which if x_8 takes a plane, then x_8 is a mechanic. From the fact that for all x_8, x_8 is a mechanic or x_8 is not an astronaut we can infer that for all x_8, if x_8 were an astronaut, then x_8 is a mechanic. Finally, from the fact that there is at least one x_8 for which if x_8 takes a plane, then x_8 is a mechanic, that for all x_8, if x_8 were an astronaut, then x_8 is a mechanic, and that for all x_8, x_8 will take a plane or x_8 is an astronaut we can infer that there is at least one x_8 for which x_8 is a mechanic. Therefore, the answer is yes.