I would appreciate some help with the question below. It is just for personal study to get ahead for next year, but the textbook doesn't have answers, and I am unsure how to do b and d specifically. I have done a as it is quite simple, and I have the an and bn general formulas, I just don't know how to use them to solve it.
Question: https://i.stack.imgur.com/xkDLc.png
