Question 664394
TREE DIAGRAM
   D,S,U,X 
     D,U,S,X
       D,X,U,S
       YOU CAN GET3X4=12 ARRANGEMENTS
 PUT THE LETTERS 3 DIFFERENT WAYS TIMES4 LETTERS=12
  D,S,U,X
  D,U,X,S
  D,X,S,U==THIS IS AN EXAMPLE OF THE THE DIAGRAM