Hello j5sawickiYou haven't made the questions clear. What, for example, does 'A is not a part of C' mean?

However, #1 looks clear enough, and your answer is incorrect. If , then you don't need the inner brackets inside set . You can just say .

And if , then needs to contain all the elements that are in , plus at least one other. You have this the wrong way round; you have .

For #2, I assume you mean and , but I don't know (as I've said) what 'not a part of' means.

If , and is itself a set, then your first answer is correct: . But it would be better if you didn't mix sets with integers in set . So would probably be a better answer.

If , then must be a set containing sets like as elements - and include itself. For instance you could have

For #3, you could have and the same as in #2, and then if must contain all the elements in , plus at least one more; for example,

Grandad