how can I solve this one?

Problem 12-2 Firm XYZ changes their process line resulting in a reduced labor cost of $50,000 per year. The change required the purchase of a segmented gate system that cost $90,000. They will produce on this line for 3 years after which they will sell the equipment for $50,000. They use straight line depreciation over 10 years. Tax rate - 40% and WACC -12%