Final answer:
Cross-price elasticity less than 0 indicates that the goods are complementary, meaning an increase in price for one leads to a decrease in demand for the other.
Step-by-step explanation:
When examining the relationship between two goods in the market, particularly how the price of one good impacts the demand for another, we look at the concept of cross-price elasticity of demand. This economic measure indicates whether goods are substitutes, complements, or unrelated. A cross-price elasticity less than 0 (a negative value) indicates that the goods in question are complementary goods. This means that when the price of one good increases, the demand for the complementary good decreases, and vice versa. For example, if good A (coffee) is a complement to good B (sugar), a higher price for sugar will result in a decreased quantity consumed of coffee.