Everybody talks about how powerful LLMs are, but neither Bard nor ChatGPT seem to come close to solving the following (easy) problem:

Given a stock portfolio with an annual return of r=5%, and the choice of either paying 30% tax on the portfolio gains each year, or paying 24% tax on the capital gains component of whatever you withdraw after 10 years, what is the actual annual return for both portfolios after 10 years?