We cannot tell what "(X  Y)  W" means.

It could be any of these 4.  

(X ⋂ Y) ⋂ W
(X ⋂ Y) ⋃ W
(X ⋃ Y) ⋂ W
(X ⋃ Y) ⋃ W

You can tell me in the answer note form below, and I'll get
back to you by email.  You can use the letter capital U for 
union, ⋃, and the little letter n for intersection, ⋂, like 
this:

(X n Y) n W
(X n Y) U W
(X U Y) n W
(X U Y) U W

Edwin