The following subsets you can be able to create are: {1} {2} {3} {1,2} {1,3} {2,3} {1,2,3} Therefore, there are 7 subsets in all. However, we don't have to list all these possible outcomes because we could waste our time doing this but there is a formula, that is 2^n - 1 where n is a number of elements.
In the given, since there are 3 elements inside the set then we use 2^3 - 1 = 8 - 1 = 7. See...it's easy.