4. An iconic New York City cake and pastry shop produces and retails 300,000 dozen cannoli a year and expects sales to remain at this level indefinitely. It buys boxes (each holds a dozen cannoli) from a paper and cardboard factory for 50 cents apiece. The shop's management is exploring the idea of making boxes themselves rather than outsourcing. If produced at the bakery, the boxes are estimated to cost only 25 cents apiece. A machine to make the boxes costs $50,000, has a useful life of 10 years, and a scrap value of $3000. Additional working capital of $15,000 would be needed. The machine can be depreciated to zero for tax purposes over 10 years. If the corporate income tax rate is 28% and the firm's discount rate is 12%, compute the NPV of producing the boxes at the shop rather than buying them outside