Please explain to me how to get the answer for 7.21, step by step because I can't figure it out. Also please show all work written down

you only need to solve for 7.21 there is nothing for 7.2

17.21] Compute the capital recovery for the machine of Problem, 7.15, using (76). Compare with the answer to Problem 7.20 (answer to 7.20 is $22 941.26 per year). Answer $2941.25 = $22 941.26 - $20 000 value [7.15] A used machine costs $20 000 to purchase. It has an annual maintenance cost of $20 000, a salvage of $5000, and a 10-year life. If the interest rate is 10% per year, compounded annually, what is the present-worth cost of the machine? Answer $140 960.12 [7.6) is below Let i = 15% per year, compounded annually. Determine the present worth of the following cash flows: End of Year 0 1 2 3 Cash Flow, $1000 - 10 2 2 6 6 Analyze the last two flows as $2000+ $4000. Then, PW-510 000 + $2000(P/A, 15%, 0)+54000(PIA, 15%, 2)(P/F, 15%, 2) =-510 000 + $2000(0.35027)+'+ 54000(0.61512) (1.3225)-' = $626.93