Your firm must purchase one of two machines. Your firm's MARR is 10%. Machine A has an initial cost of $1,000 and a working life of 4 years. Machine A will provide savings of $400 per year and can be salvaged for $656 at the end of its working life. Machine B has an initial cost of $250 and a working life of 2 years. Machine B will provide savings of $200 per year and can be salvaged for $225 at the end of its working life. The appropriate project lifetime to use for the repeated lives method is years. Using the present worth, repeated lives method, your firm will compare a net present value of for Machine A to a net present value of for Machine B, and decide that Machine is the best purchase