Oyster crackers are a complement for clam chowder. If the price of clam chowder falls, the quantity of clam chowder demanded , which the demand for oyster crackers. Because of the change in the equilibrium quantity of oyster crackers, the demand for wheat flour by oyster crackers producers , causing the equilibrium price of wheat flour to . This means producers of bread face input prices, and the supply of bread . The resulting in the price of bread causes people to substitute , so the demand for cereal .