Four distinct letters are to be drawn from the set {A,B,C,D,E,F and G}. You are to create sub -sets out of these letters. Examples of a sub-set would be {A,C,D,F}, {E,B,D,G}etc. A sub-set is like grouping the letters into smaller sets. How many four letter sub-sets are possible that contain either A or E, but not both