Question on Sets, please help (1 Viewer)

[jackerino]

Can anyone at least point me in the right direction plz? with this 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?

Note: I am familiar with sets and the language of sets, our teacher just gave us this question as a test to see if we knew how to do it, and Idk LOL. Can someone explain please?

 

[jackerino]

Also just checking this, if a,b an c are the roots of x^3+4x^2-6x-8=0, to find
(1/a)+(1/b)+(1/c). i multiply through to get (ab+ac+bc)/(abc) right?

and to find

(1/ab)+(1/ac)+(1/bc) I multiply through to get (abc^2+ab^2c+a^2bc)/(a^2.b^2.c^2) right? just checking my methodology