Cookies and Milk
The Perfect Pair
A Good Snack
If demand for chocolate chip cookies goes up, the demand for milk will also be likely to go up. Milk and cookies are related goods and milk is a good compliment to cookies. Therefore, people will usually buy milk if they buy cookies.
Sugar Cookie Prices Decrease
Sugar cookies and chocolate chip cookies are related goods. Sugar cookies are a substitute for chocolate chip cookies. So, if sugar cookies go on sale, the demand for chocolate chip cookies will decrease because they are more expensive and sugar cookies are a good substitute.