Question 143001
Here are all of the possible subsets of {a,b,c,d}


{a,b,c,d},
{a,b,c},{a,b,d},{a,c,d},{b,c,d},
{a,b},{a,c},{a,d},{b,c},{b,d},{c,d},
{a},{b},{c},{d},{ }


note: the last set { } is the null set or the empty set