Hi folks,
I am helping my brither with algebra, but I am not familiar with those symbols in the answer section. What do they mean? How should we approach this problem? I'm used to seeing equations in algebra, not this.

Hi folks,
I am helping my brither with algebra, but I am not familiar with those symbols in the answer section. What do they mean? How should we approach this problem? I'm used to seeing equations in algebra, not this.

a) What's to the left of the symbol "is a subset of" what's to the right of the symbol.
b) What's to the right of the symbol "is a subset of" what's to the left of the symbol.
c) What's to the left of the symbol "is NOT a subset of" what's to the right of the symbol.