Consider the following premises. If David drinks water, then it is snowing. Charles is driving a car if and only if it is snowing. David is drinking water if and only if Charles is driving a car. Can we infer the following from them? If we can, name the inference rule being used: If David drinks water, then Charles is driving a car.
 From the fact that Charles is driving a car if and only if it is snowing we can infer that if it snows, then Charles is driving a car via biconditional elimination. From the fact that David is drinking water if and only if Charles is driving a car we can infer that if Charles drives a car, then David is drinking water via biconditional elimination. Finally, from the fact that if David drinks water, then it is snowing, and that if it snows, then Charles is driving a car we can infer that if David drinks water, then Charles is driving a car via transitivity. Therefore, the answer is yes.