Describe how a change in the price of a product affects the optimal bundle of a consumer. For example, when the price of one product increases, what happens to the optimal quantity of both products? How does such a change in the optimal bundle describe the demand curve of one of the products in the bundle? If the price of one product changes and the optimal bundle changes as a result, then what does this tell us about complementary and substitute products (which we learned about in Module 1)?