She should charge 52 dollars for each lamp.
Work Step by Step
Let s represent the selling price. The basic relationship is: selling price equals cost plus profit. Selling price = Cost + Profit Selling price = s Cost = 40 Profit = 30% $\times$ 40 = .3 $\times$ 40 = 12 Substitute these values into the equation to obtain: s = 40 + 12 s = 52 She should charge 52 dollars for each lamp.