Consider the following premises. For all x_8, x_8 is a scientist. For all x_8, x_8 is a scientist if and only if x_8 is a mechanic. For all x_8, x_8 will climb a mountain. Can we infer the following from them? For all x_8, x_8 is a mechanic.
 From the fact that for all x_8, x_8 is a scientist if and only if x_8 is a mechanic we can infer that for all x_8, if x_8 were a scientist, then x_8 is a mechanic. Finally, from the fact that for all x_8, if x_8 were a scientist, then x_8 is a mechanic, and that for all x_8, x_8 is a scientist we can infer that for all x_8, x_8 is a mechanic. Therefore, the answer is yes.