As said in the title, this the problem I'm supposed to solve (really feeling rather stupid even asking this question, but oh well..):
Let there be sets $A$, $B$, $C$. Find all sets $X$ so that $A\cap X=B$ and $A\cup X=C$
I am very new to all of this, so I don't know how to write down what I'm thinking. In my mind I get to the point that all sets $X$ are defined here as $X \setminus (A\setminus A\cap X)$. But perhaps I am thinking the wrong way and not at all getting what I'm asked to do. Any help in this matter?