Consider the following premises. For all x_9, x_9 will not make tea. For all x_9, x_9 will go running if and only if x_9 will make tea. Charles is running if and only if it is windy. Can we infer the following from them? If we can, name the inference rule being used: It is not windy.
 From the fact that for all x_9, x_9 will go running if and only if x_9 will make tea, and that for all x_9, x_9 will not make tea we can infer that for all x_9, x_9 will not go running via universal biconditional elimination. From the fact that for all x_9, x_9 will not go running we can infer that Charles is not running via universal instantiation. Finally, from the fact that Charles is running if and only if it is windy, and that Charles is not running we can infer that it is not windy via biconditional elimination. Therefore, the answer is yes.