$2.$ Sun Brite has a new pair of sunglasses it is evaluating. The company expects to sell $5,300$ pairs of sunglasses at a price of $$148$ each and a variable cost of $$100$ each. The equipment necessary for the project will cost $$280,000$ and will be depreciated on a straight$-$line basis over the $9-$year life of the project. Fixed costs are $$140,000$ per year and the tax rate is $21$ percent. How sensitive is the operating cash flow to a $$1$ increase in variable costs per pairs of sunglasses?