Subtract previous data with mdx

Question

I have this mdx query:

    SELECT 
  NON EMPTY 
    Hierarchize({DrillDownLevel({[Date].[Date].[All]})})
  DIMENSION PROPERTIES 
    PARENT_UNIQUE_NAME
   ,[Date].[Date].[Date].[Month]
   ,[Date].[Date].[Date].[Week]
   ON COLUMNS
 ,NON EMPTY 
    Hierarchize({DrillDownLevel({[Work Item].[System_AssignedTo].[All]})})
  DIMENSION PROPERTIES PARENT_UNIQUE_NAME  ON ROWS
FROM [Team System]
WHERE 
  (
    [Work Item].[Iteration Hierarchy].[Iteration1].&[4088869461251342155]&[-8859253554898915707]
   ,[Measures].[Microsoft_VSTS_Scheduling_RemainingWork]
  )
CELL PROPERTIES 
  VALUE
 ,FORMAT_STRING
 ,LANGUAGE
 ,BACK_COLOR
 ,FORE_COLOR
 ,FONT_FLAGS;

that return to me the sum of the remaining work per people divided by day. How i can obtain some like that but with the differenc between a day data and the previous day?

Thank you

Enri