Consider the following premises. Jennifer is not playing a game. If Robert were a writer, then Mary is not happy. For all x, x is sad if and only if x will play a game. Mary is happy. Can we infer the following from them? Jennifer is sad.
 From the fact that if Robert were a writer, then Mary is not happy, and that Mary is happy we can infer that Robert is not a writer. From the fact that for all x, x is sad if and only if x will play a game we can infer that Jennifer is sad if and only if Jennifer is playing a game. Finally, from the fact that Jennifer is sad if and only if Jennifer is playing a game, and that Jennifer is not playing a game we can infer that Jennifer is not sad, which contradicts that Jennifer is sad. Therefore, the answer is no.