I notice you answer many maths problems, could you perhaps help me please with a sets question?
let S=(a,b,c,d,e,f,g,h,i,j) be the set consisting of the first ten letters of the alphabet.
i) How many subsets of S contain at least three letters?
ii) How many subsets with at least three letters do not contain any vowels?
iii) How many subsets with at least three letters do not contain any vowels but do contain the letter "b"?
Please help me!