I'm having trouble getting started with the following question:
Find counterexamples to the following statements.
How should I make stuff up?
whether this statement is correct or not, it is not what you were asked to show. you were asked to find a counter-example, that is, sets A and B for which:
so you should have a statement like:
but ,
for some specific A and B (one example, not a general case which the counter-example "proves").