Consider the following premises. For all z_1, if z_1 takes a plane, then z_1 is playing tennis. James is excited or Sarah is not playing tennis. If James were excited, then Sarah is taking a plane. Can we infer the following from them? If is not true that James is excited if and only if Sarah is playing tennis.
 From the fact that for all z_1, if z_1 takes a plane, then z_1 is playing tennis we can infer that if Sarah takes a plane, then Sarah is playing tennis. From the fact that James is excited or Sarah is not playing tennis we can infer that if Sarah plays tennis, then James is excited. From the fact that if James were excited, then Sarah is taking a plane, and that if Sarah takes a plane, then Sarah is playing tennis we can infer that if James were excited, then Sarah is playing tennis. Finally, from the fact that if James were excited, then Sarah is playing tennis, and that if Sarah plays tennis, then James is excited we can infer that James is excited if and only if Sarah is playing tennis, which contradicts that If is not true that James is excited if and only if Sarah is playing tennis. Therefore, the answer is no.