P.hD questions

A. Assume ABC purchase a delivery truck for $7,200. The truck has a useful life 8 years with a salvage value of $800. Assume also that the truck reduces annual shipping cost by $15,000 but has additional shipping cost for a driver $9,000, and for the upkeep of the driver at $3,000, all making a total of $13,000 per year. If the tax rate is 50% and the cost of capital is 10% for the company under the straight line depreciation method, determine whether the project should be undertaken or not.
B. Assuming that a new machine if purchased will enable the firm increase annual sales by $600, increase cost of goods sold by $2,500, increases operating cost by $500, producing a new rise in the firms pre-tax cash flow of $3,000 annually ($6,000 -$2,500 and $500). If the new machine cost $6,000 with a five years life but without a salvage value. Determine whether the investment should be made and why?