How do I do this? (The Chegg explanation online does not show how the numbers were calculated, can you show how the numbers are calculated if not given?)Below is the question info:

The controller of Tim's Travel is deciding between upgrading the company's existing computer system or replacing it with a new one. Upgrading the four-year-old system will cost $97,500 and extend its useful life for another seven years. The book value is $19,500, although it would sell for $24,000. Upgrading will eliminate one employee at a salary of $19400; the new computer will eliminate two employees. Annual operating costs are estimated at $15,950 per year. Upgrading is expected to increase profits 3.5% above last year's level of $553,000. The BetaTech Company has quoted a price of $224,800 for a new computer with a useful life of seven years. Annual operating costs are estimated to be $14,260. The average processing speed of the new computer is 12% faster than that of other systems in its price range, which would increase TT's profits by 4.5%. Tim's present tax rate is 35%, and the cost of financing is 11%. After seven years, the salvage value, net of tax, would be $12,000 for the new computer and $7500 for the present system. For tax purposes, computers are depreciated over five full years(six calendar years ; a half year the firs and last years), and the depreciation percentages are as follows: Year 1(20%), Year 2(32%), year 3(19.20%), year 4(11.52%), year 5(11.52%), year 6(5.76%)

Directions: Using a spreadsheet package, prepare an economic feasibility analysis to determine whether TT should rehabilitate the old system or purchase the new computer. As part of the analysis, compute the after-tax cash flows for years 1 through 7 and the payback, NPV, and IRR of each alternative.