The estimates for three alternatives are to be compared on the basis of their perpetual equivalent annual worth. At an interest rate of 10% per year, what is the AW of Z12 Alternative First Cost Annual Cost Salvage Value Life Years X1 -50,000 -10,000 13,000 3 Y1 -90,000 -4,000 15,000 6 zi -64,000 -8,000 11,000 9 -22,721 O-21,269 - 12,627 O-11,056 -18,803