Consider the following premises. For all x_5, x_5 will drive a car if and only if x_5 is a scientist. For all x_5, if x_5 were a scientist, then x_5 is a server. For all x_5, if x_5 were a server, then x_5 is happy. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_5 for which the fact that x_5 drives a car does not imply that x_5 is happy.
 From the fact that for all x_5, if x_5 were a scientist, then x_5 is a server, and that for all x_5, if x_5 were a server, then x_5 is happy we can infer that for all x_5, if x_5 were a scientist, then x_5 is happy via universal transitivity. From the fact that for all x_5, x_5 will drive a car if and only if x_5 is a scientist we can infer that for all x_5, if x_5 drives a car, then x_5 is a scientist via universal biconditional elimination. Finally, from the fact that for all x_5, if x_5 drives a car, then x_5 is a scientist, and that for all x_5, if x_5 were a scientist, then x_5 is happy we can infer that for all x_5, if x_5 drives a car, then x_5 is happy via universal transitivity, which contradicts that There is at least one x_5 for which the fact that x_5 drives a car does not imply that x_5 is happy. Therefore, the answer is no.