First, I am not sure how to type the correct characters into this message block. I tried character map, but I had no luck. IF anyone wants to tell me if there is a language pack or add-on for this, feel free. Now the proof I am working on is as follows:

prove that $\displaystyle A \subseteq B$ if and only if "the complement of B" $\displaystyle \subseteq $ "the complement of A"

Can someone point me in the right direction? Again any help inputting the symbols is appreciated as well.