Please show work when possible

You purchase a U.S. Treasury STRIPS today with exactly 15 years remaining maturity for $424.17. You hold this STRIPS for 3 years, and then sell it in the market for $540.09 on that date. You are in the 35% federal income tax bracket, and you pay 20% tax on capital gains. Ignore state taxes. Calculate the net aftertax cashflows from owning this STRIPS in each of years 1, 2 and 3. What is your aftertax holding period yield (HPY) during this time period?