Please explain the following thoroughly (explain the book value, after tax salvage value, operating cash flows for each year, and how to find the NPV) I use a financial calculator to find NPV.

Geary Machine Shop is considering a four-year project to improve its production efficiency. Buying a new machine press for $720,000 is estimated to result in $240,000 in annual pretax cost savings. The press falls in the MACRS five-year class (MACRS Table), and it will have a salvage value at the end of the project of $105,000. The press also requires an initial investment in spare parts inventory of $30,000, along with an additional $4,500 in inventory for each succeeding year of the project. If the shop's tax rate is 35 percent and its discount rate is 15 percent, what is the NPV for this project?