For this discussion, think about where you work or a business you have a significant amount of knowledge about. What is a common product that the business sells? What are the main costs the business has to incur in order to be able to sell that product? Which of these costs are fixed and which are variable? How much additional costs would be incurred if it were to sell one additional unit of that product (marginal cost)?
Write a discussion thread about this business, the product it commonly sells, and your answers to the above questions.