What is the result of A, B, and C when using the subset formula?

[Mokae]

A U B = X
C U B = Y
C U A = Z

knowing that A U B is the child of Y and Z
Cold you help me rewiete the formila ?

Thank you

 

[HallsofIvy]

?? Define "child".

 

[Mokae]

I meant subset.
I don't know how to use only U to display the relation