Post completion audit question

AB is conducting a post completion audit on an investment in a pollution control machine that has reached the end of its 5 year useful life.
AB could face next fines if the machine called to keep with the output of emissions.
ABs cost of capital is 10%. There was a choice of 3 machines in the market. AB purchased the Big machine, but annual requirements exceeded 600,000 once, in year 3, when 720000 units of emission were emitted.
Calculate the amount that the post completion audit shows AB overpaid for the ownership costs associated with this machine.

Can you please do the working here. The answer is $12582000