annual net operation cash flow

revenue: $100,000 labor and material cost: 20,000 depreciation: 10,000 tax rate: 0.35 to determine the project’s net present value, the amount of annual net operation cash fhow should be calcualted: I use (revenue - labor and material cost-depreciation)*(1-0.35)+ depreciation, but could not get the correct answer. sorry, could not dig into the pile of my manual to find the exact way of calculation, any body shed some light? Thanks.

(Revenue - labor & material cost - depreciation) * (1 - tax rate) = net income Add back depreciation to arrive at the net operating cash flow.