We have two sets of letters [tex]B=\{d,f,g\}[/tex] and [tex]G=\{a,d,h\}[/tex].
Intersection of sets [tex]B[/tex] and [tex]G[/tex] is set [tex]I[/tex] that contains elements that are common to [tex]B[/tex] and [tex]G[/tex], mathematically
[tex]I=\{x:x\in B\wedge x\in G\}[/tex]
Or simply [tex]I=B\cap G=\{d\}[/tex].
Union if sets [tex]B[/tex] and [tex]G[/tex] is set [tex]U[/tex] that contains elements from [tex]B[/tex] or [tex]G[/tex] thus
[tex]U=\{x:x\in B\vee x\in G\}[/tex]
Or again simply [tex]U=B\cup G=\{d,f,g,a,h\}[/tex].
Hope this helps.
