Sally’s company has been selling lamps at the price of $50 per lamp, and at this price consumers have been buying 3,000 lamps a month. Sally wishes to lower the price and estimates that for each $1 decrease in the price, 1,000 more lamps will be sold each month. She can produce the lamps at a cost of $29 per lamp. Express Sally’s monthly profit as a function of the price that the lamps are sold, draw the graph, and estimate the optimal selling price.