Consider the following premises. If it snows, then Patricia is playing tennis. If Patricia were a sailor, then it is snowing. For all x_10, if x_10 plays tennis, then x_10 is a sailor. Can we infer the following from them? Patricia is playing tennis if and only if Patricia is a sailor.
 From the fact that for all x_10, if x_10 plays tennis, then x_10 is a sailor we can infer that if Patricia plays tennis, then Patricia is a sailor. From the fact that if Patricia were a sailor, then it is snowing, and that if it snows, then Patricia is playing tennis we can infer that if Patricia were a sailor, then Patricia is playing tennis. Finally, from the fact that if Patricia plays tennis, then Patricia is a sailor, and that if Patricia were a sailor, then Patricia is playing tennis we can infer that Patricia is playing tennis if and only if Patricia is a sailor. Therefore, the answer is yes.