Sammie has 4 ½ cups of flour. She needed to know if she had enough flour to make two cakes. She needs 2 1/8 cups of flour for a lemon cake and 2 ¾ cups of flour for her chocolate cake. Sammie determined that she would need 4 7/8 of flour and went to the store to buy more. How did Sammie determine how much flour she would need?
(She added the flour needed for each recipe; 2 1/8 + 2 ¼.