Phileas, the Lumbridge Sage, is part of the council and needs your help. Since his job is to explain basic parts of the game to new adventurers, he will want a Cake of Guidance. Great, but... what on Gilenor is a Cake of Guidance?
Wizard Traiborn, at the Wizard's Tower, can help you with that. It turns out that a Cake of Guidance is a normal cake, but with the ingredients enchanted with knowledge. To do that, Traiborn will have you complete two short quizzes and a memory test. Once you've completed these correctly, the ingredients are enchanted and you just have to bake them like you would a regular cake and feed the Lumbridge Sage the result.
Congratulations, subquest complete!