Please Refrain from using Excel Thanks!

4) a) You decide that your family would be comfortable living on an annual income of $150,000, growing at 4% per year. You'd also like to continue generating this cash flow for your descendants, forever. With interest rates of 8%, how much wealth would you need today to provide this income starting with S150,000 one year from now? b) Suppose all income is taxed at 20%. How would this (if at all) change your answer to a)? Assume that you still feel 4% growth and $150,000 (after-tax) income is sufficient. Show a calculation and briefly explain