There are indeedsubsets of A.

BUT, that is not the way you have worded the question.

You have ask “how many subsets of {1,2,3,…,100} aresupersets of A?”

That is how many subsets of {1,2,3,…,100} have A as a subset.

The answer to that is . So which is your question?

Is it about subsets of A? Or is it about supersets of A?

There is no point in my guessing which question you need help with.