Consider the following premises. Thomas is not excited. If Richard were bored, then it is overcast. Thomas is excited if and only if Sarah is reading a book. Richard is writing a letter or Sarah is reading a book. If Richard writes a letter, then Richard is bored. Can we infer the following from them? If we can, name the inference rule being used: Charles is a lawyer.
We cannot infer that from the premises. Therefore the answer is no.