Consider the following premises. Linda is playing squash or Jennifer is a server. It is sunny if and only if Linda is playing squash. If Jennifer were a server, then it is sunny. Can we infer the following from them? It is sunny or Susan is poor.
 From the fact that it is sunny if and only if Linda is playing squash we can infer that if Linda plays squash, then it is sunny. From the fact that if Linda plays squash, then it is sunny, that if Jennifer were a server, then it is sunny, and that Linda is playing squash or Jennifer is a server we can infer that it is sunny. Finally, from the fact that it is sunny we can infer that it is sunny or Susan is poor. Therefore, the answer is yes.