How was the Net Working Capital Cash Flow calculated in the chart?

Year 1 Year 2Year 3Year 4Year 5 Particulars amount in amount in amount in amount in amount in Net sales Less: Net Variable cost Fixed costs 6,100,000 6,100,000 6,100,000 6,100,000 6,100,000 Depreciation 5,787,450 2,918,450 Z,083.450 5,058,450 3,616,650 EBT Less: Tax 6,050,643 Z,457,293 8,722,543 6,235,793 4,605,423 Net Income 11,236,90813,849,25816,212,008 11,580,7588,552,92:8 Add :Depreciation OCF Net working capital cash flows Net cash low 58,150,000 68,450,000 65,000,00049,400,00039,000,000 28,975,000 31,125,000 26,875,000 20,425,000 16,125,000 17,287,550 21,306,550 24,941,550 17,816,550 13,158,350 5,787,450 2,918,450 2,083,450 5,058,450 3,616,650 17,024,35823,767,708 23,295,458 16,639,208 12,169,578 0,000)(2,60,000) 690,000 3,120,000 2,880,000 5,394,358 21,707,708 23,985,458 19,759,208 22,049,577