Consider the following premises. If it snows, then Richard is not a janitor. Sarah is drinking water. Barbara is listening to a song and it is late. If Sarah drinks water, then Richard is a janitor. Can we infer the following from them? If we can, name the inference rule being used: It is snowing.
 From the fact that if Sarah drinks water, then Richard is a janitor, and that Sarah is drinking water we can infer that Richard is a janitor via modus ponens. Finally, from the fact that if it snows, then Richard is not a janitor, and that Richard is a janitor we can infer that it is not snowing via modus tollens, which contradicts that It is snowing. Therefore, the answer is no.