dnt solve it by Excel program ,, solve it by hand show me formulas to make me able to understand it,, if you are not able to solve it by hand dont solve it please i dont want to lose a question without gitting a usefull answer, there is no salvage value in the question,, i have posted the same question here but i just got a solve with excel but i dont need excel solution i need it with formulas and on hand, i dont want to lose a question and have the same answer that i got before here i mean by excel..

Question The Government is considering building apartments for government employees working in a foreign country and currently living in locally-owned housing. A comparison of three possible buildings indicates the following: Building X Building Y Building Z Original investment $8,000,000 $12,000,000 $10,000,000 Estimated annual maintenance costs $240,000 $180,000 $210,000 Savings in annual rent now being paid to $1,960,000 $1,320,000 $1,640,000 house employees Service life 18 27 25 Assuming that the do-nothing alternative is not feasible and using an interest rate of 10%, make a selection recommendation about the best option using Present Worth Analysis for a study period of 18 years