Mixtures are made up of what substances.

Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule. A mixture is composed of different types of atoms or molecules that are not chemically bonded.

It would depend on the mixture to determine what the mixture is.

Explanation:

If you don't know what the mixture is then you wont be able to find what substances, since their could be many components.