let me explain how to deal with NPV. First you should know the two terms
1. Cost of the project (outflow, investment)
This means what is the cost of the building, equipment..etc it is always multiplied by NPV of 1, therefore, if the cost of the equipment 10,000, NPV of it is 10,000 there is no change
2. Cash inflows:
There are two things that bring cash flows. First: AFTER Tax (not before be-careful) annual cash flows that comes from the project.
Second: depreciation tax shield ( Cost of the project / No. of years) * tax rate
Then Add (first+second from above) x NPV factor
Now apply the above in this formula
NPV = Cash inflows – Cost of the project