6. Spreadsheet Problem. Use the Ch7 Rent_vs_Own worksheet in the Excel workbook provided on the Web site. Determine the after-tax IRR for owning versus renting in each of the five years with the following changes in the original assumptions in the spreadsheet: a. The homeowner has a 15 percent marginal tax rate instead of 28 percent. b. Rents and property values will not increase over the five years. c. The loan amount is $105,000 instead of $120,000. d. The initial rent for year 1 is $15,000 instead of $12,000.