Problem: Give an example of each a commonly owned substitute and commonly owned complement. Try to use complements other than the product and accessory pack specifically for that product (like a Dremel tool and associated attachments that you need the main tool to use the attachment). You must list the company owning each product. Why are the products substitutes and complements? Do you believe the companies engage in optimal pricing?
The same company must manufacture both substitutes and the same company must manufacture complements, but the company making the two substitutes can differ from the one making the complements. To clarify you might have 2 different companies, one that makes 2 substitute products and one that makes 2 complementary products, or one company that makes 2 of each.