please answer following questions with step thank you so much.

4) I have a 20% marginal tax rate. I can choose between a corporate bond that pays $100 per year and a municipal bond that pays $90 per year. Both bonds are equally risky. Which do I prefer? 5) I have a 30% marginal tax rate. Taxable corporate bonds are paying 5%. What yield would I require for an equally risky tax- free bond? Questions 6 and 7 relate to the slide set for chapter 4 6) An index fund charges an expense ratio of 0.1%. An active fund charges an expense ratio of 0.8%. The active fund picks better stocks, so the active fund's holdings (before expenses) outperform the index fund's holdings by 0.5%. Which fund would you rather hold, and by how much will this fund beat the other fund