Combine the sugar, shortening and egg. Ad mashed banana, baking soda and water. Add flour, baking powder, salt and vanilla. Mix well. Bake in a greased and floured 9x9" baking pan at 350ºF.  for 30-35 minutes or until cake tests done. Cool. Frost with banana frosting or use lemon or orange frosting. Banana Frosting: Mash banana. Add vanilla and margarine. Add sugar to make correct consistency for spreading. Can add dash lemon juice to add tartness.