over the 4 year analysis period the present value of machine

A manufacturer with a MARR of 20% is considering the installation of one of three packaging machines. The economic parameters of each machine are as follows: Packaging machine: x z Initial cost ($) 20,000 40,000 15,000 Uniform annual benefit ($) 120,000 180,000 100,000 Uniform annual O&M cost ($) 70,000 50,000 70,000 Service life (years) 6 3 12 Salvage value end of life ($) 2,000 4,000 2,000 Which choice below gives the correct PW equation for machine X over the appropriate analysis period