Consider the following premises. For all x_5, if x_5 drinks water, then x_5 is happy. For all x_5, if x_5 were happy, then x_5 is drinking water. For all x_5, if x_5 were happy, then x_5 is drinking water. Can we infer the following from them? For all x_5, x_5 is happy if and only if x_5 will drink water.
Yes.