solve using excel show functions. my answer is wrong i believe i was told it cannot be negative. just start fresh and ignore what i have

Calculate operating cash flow in Year 5 for a product as follows: 1,500 units sold for 20 apiece; fixed costs are 21,500 , variable costs are 7.50 a unit; fixed assets of 20,000 are depreciated on a straight-line basis over the 5-year life with salvage value of 6,000 . As usual, the tax rate is 21%