Consider the following premises. For all x, if x drinks water, then x is a cashier. For all x, x is a cashier if and only if x is happy. There is at least one x for which x will drink water or x is happy. Can we infer the following from them? For all x, neither x is a cashier nor x will listen to a song.
 From the fact that for all x, x is a cashier if and only if x is happy we can infer that for all x, if x were happy, then x is a cashier. From the fact that for all x, if x drinks water, then x is a cashier, that for all x, if x were happy, then x is a cashier, and that there is at least one x for which x will drink water or x is happy we can infer that there is at least one x for which x is a cashier. Finally, from the fact that there is at least one x for which x is a cashier we can infer that there is at least one x for which x is a cashier or x will listen to a song, which contradicts that For all x, neither x is a cashier nor x will listen to a song. Therefore, the answer is no.