Given that C = {x : x is a letter in the word ‘ASSASSINATION’}
The roster form of the set C = {,,,,,}, since elements in a set cannot be repeated.
Also given that B = {x : x is a letter in the word STATION}
‘B’ can also be written as B = {,,,,,}
So, the elements of C and B are same and C = .
i.e. C ⊆ B, B ⊆ C ⇒ C=