Consider the following premises. Patricia is taking a plane if and only if it is raining. For all x_7, x_7 will play squash if and only if x_7 will take a plane. It is not raining. Can we infer the following from them? If we can, name the inference rule being used: Patricia is not playing squash.
 From the fact that for all x_7, x_7 will play squash if and only if x_7 will take a plane we can infer that Patricia is playing squash if and only if Patricia is taking a plane via universal instantiation. From the fact that Patricia is taking a plane if and only if it is raining, and that it is not raining we can infer that Patricia is not taking a plane via biconditional elimination. Finally, from the fact that Patricia is playing squash if and only if Patricia is taking a plane, and that Patricia is not taking a plane we can infer that Patricia is not playing squash via biconditional elimination. Therefore, the answer is yes.