which of the following sets is a subset

of A?

A:5,25,15,10,20,30

not just and answer

A.5,15,60
B.10,20,50
C.5,10,20
D.15,30,60

well i got the answer C

3 answers

Right.
http://www.mathsisfun.com/sets/sets-introduction.html
but i'm not so good at subsets can you explain, so i can maybe understand in a different way.
Please study the site I linked above.