How many subsets of the set {1,2,3,4,5} contain the number 5?
List them ...
{5}
{1,5} {2,5} {3,5} {4,5}
{1,2,5} {1,3,5} {1,4,5} (2,3,5} {2,4,5} {3,4,5}
{1,2,3,5} {1,2,4,5} {1,3,4,5} {2,3,4,5}
{1,2,3,4,5}
