Consider the following premises. Charles is an office clerk if and only if Jessica is playing squash. If it is windy, then Jessica is playing squash. If Charles were an office clerk, then it is windy. Can we infer the following from them? If we can, name the inference rule being used: Jessica is playing squash if and only if Charles is an office clerk.
 From the fact that if Charles were an office clerk, then it is windy, and that if it is windy, then Jessica is playing squash we can infer that if Charles were an office clerk, then Jessica is playing squash via transitivity. From the fact that Charles is an office clerk if and only if Jessica is playing squash we can infer that if Jessica plays squash, then Charles is an office clerk via biconditional elimination. Finally, from the fact that if Jessica plays squash, then Charles is an office clerk, and that if Charles were an office clerk, then Jessica is playing squash we can infer that Jessica is playing squash if and only if Charles is an office clerk via biconditional introduction. Therefore, the answer is yes.