Answer:
Based on the data, net cash flows (NCFs) before replacement are $1,680 and they are constant over four years.
Step-by-step explanation:
annual operating costs before replacement = $1,100
sales revenue = $3,500
depreciation of old machine = $600
tax rate = 40%
net cash flow = [(revenues - current cost - depreciation) x (1 - tax rate)] + depreciation = [($3,500 - $1,100 - $600) x (1 - 40%)] + $600 = $1,680 per year