Consider the following premises. It is sunny or Richard is taking a plane. Charles is sleeping if and only if Richard is taking a plane. Charles is not sleeping. If it is sunny, then Linda is driving a car. If Linda drives a car, then Jessica is writing a letter. Can we infer the following from them? Jessica is writing a letter.
 From the fact that Charles is sleeping if and only if Richard is taking a plane, and that Charles is not sleeping we can infer that Richard is not taking a plane. From the fact that it is sunny or Richard is taking a plane we can infer that if Richard doesn't take a plane, then it is sunny. From the fact that if it is sunny, then Linda is driving a car, and that if Linda drives a car, then Jessica is writing a letter we can infer that if it is sunny, then Jessica is writing a letter. From the fact that if Richard doesn't take a plane, then it is sunny, and that if it is sunny, then Jessica is writing a letter we can infer that if Richard doesn't take a plane, then Jessica is writing a letter. Finally, from the fact that if Richard doesn't take a plane, then Jessica is writing a letter, and that Richard is not taking a plane we can infer that Jessica is writing a letter. Therefore, the answer is yes.