A set with 9 elements has 2^9 = 512 subsets.
If the universal set contains N elements then it has 2N subsets.
To find how many proper subsets there are in a set you can use the formula n^2 -n and if you would also like to find all subsets including improper the formula is n^2 -n +1
The empty set has only one subset: itself. It has no proper subsets.
If you have a set of 6 elements, you can make a total of 26 different subsets - including the empty set and the set itself.
That means, figure out how many different subsets a set has. In general, if a set has n elements, it has 2n different subsets.