S={1,{a,c},b,c}?

Hi, can someone help me ou with this, i have no idea how to do it.





Given set S={1,{a,c},b,c}





- P(A) or 2^A





- If the number of proper subsets of a set is 31, then what is the number of elements of this set?





thanks so much:P

S={1,{a,c},b,c}?
5, assuming a proper subset is not empty





P(S) means the 'powerset' of S. it is the set of all subsets of S