What do you mean by complements? Give examples of two goods which are complements of each other.
Those goods that are consumed together are called complementary goods. Example: Tea and sugar. If the price of sugar increases, then it will lead to a decrease in the demand for tea. If the price of tea increases, then it will reduce the demand for sugar.
The demand for a good moves in the opposite direction of the price of its complementary goods. That is,
If the price of tea (PT) increases, then the demand for sugar (DS) decreases.
If the price of sugar (PS) increases, then the demand for tea (DT) decreases.