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A stamping machine currently has a salvage value of $10 000, and this will drop by 20% per year from now on. Its expected maintenance costs are $1 000 for this year, but in the following year it is expected to need a major overhaul, costing $3 500. In the year following the overhaul, its maintenance costs will be $500, and these will then go up by 30% per year. Your MARR is 10%. There is a challenger available that will do the same job for an EAC of $3 400. When should you replace the old machine? in six years time O in eight years time O in two years time O in four years time right now