Q. A retailer can obtain digital cameras from the manufacturer at a cost of $150 apiece. The retailer has been selling the cameras at the cost of $340 apiece also at this cost, consumers have been buying 40 cameras a month. The retailer is planning to lower the costs to stimulate sales also estimates that for each $5 reduction in the cost, 10 more cameras will be sold each month. Express the retailer's monthly profit from the sale of the cameras as a function of the selling cost. Estimate the optimal selling cost.