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 Z1? 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 21 -64,000 -8,000 11,000 9 -12,627 -21,269 -22,721 -18,803 -11,056