How to sum and subtract in a single query

Sum(T3.U_SST_Nr_Act_AirQTY+T3.U_SST_Nr_Act_BAQTY+T3.U_SSt_Nr_Act_CourQTY+T3.U_SST_Nr_Act_SeaQTY) as 'ACTQTY'

sum(Sum(T3.U_SST_Nr_Act_AirQTY+T3.U_SST_Nr_Act_BAQTY+T3.U_SSt_Nr_Act_CourQTY+T3.U_SST_Nr_Act_SeaQTY) as 'ACTQTY'

SELECT T3.[DocNum] AS 'Document Number', T3.[CardCode] AS 'Customer/Supplier No.', T3.[CardName] AS 'Customer/Supplier Name', T2.[ItemCode] AS 'Item No.', 

T2.[Quantity] AS 'Quantity',
(T3.U_SST_Nr_Act_AirQTY+T3.U_SST_Nr_Act_BAQTY+T3.U_SSt_Nr_Act_CourQTY+T3.U_SST_Nr_Act_SeaQTY) as 'SumQty',
((T2.Quantity)-sum(T3.U_SST_Nr_Act_AirQTY+T3.U_SST_Nr_Act_BAQTY+T3.U_SSt_Nr_Act_CourQTY+T3.U_SST_Nr_Act_SeaQTY)) AS 'ACTQTY',
 
 T2.[U_ALP_DateETA] AS 'ETA', T3.[DocDueDate] AS 'Value Date', T3.[DocDate] AS 'Posting Date', T3.[U_DateArtwkappCUST] AS 'DtArtwCusAppr', T3.[U_DateProdctionApp] AS 'DateAppProd', T3.[U_ETA_UK_arrival] AS 'ETA_UK_arrival', T3.[U_Cutting_start] AS 'Cutting_start', T3.[U_CuttingStartACT] AS 'CuttingStartACT', T3.[U_CuttingEndACT] AS 'CuttingEndACT', T3.[U_Print_start] AS 'Print_start', T3.[U_PrintStartACT] AS 'PrintStartACT', T3.[U_PrintEndACT] AS 'PrintEndACT', 

T3.[U_Ex_factory] AS 'Predicted Factory Exit', T3.[U_ExFactoryACT] AS 'ExFactoryACT', T2.[U_ALP_DespatchMethod] AS 'Despatch Method', T3.[U_ETAUKArrivalACT] AS 'ETAUKArrivalACT',
 T3.[U_ALP_TrackRef] AS 'Tracking Reference',  T3.[U_SST_Nr_ACT] AS 'SST_Nr_ACT', T3.[U_SST_Nr_Act_Air] AS 'SST_Nr_Act_Air',
   T3.[U_SST_Nr_Act_AirQTY] AS 'SST_Nr_Act_AirQTY',
 T3.[U_SST_Nr_Act_BA] AS 'SST_Nr_Act_BA', T3.[U_SST_Nr_Act_BAQTY] AS 'SST_Nr_Act_BAQTY', 
 T3.[U_SST_Nr_Act_Sea] AS 'SST_Nr_Act_Sea', T3.[U_SST_Nr_Act_SeaQTY] AS 'SST_Nr_Act_SeaQTY',
 T3.[U_SSt_Nr_Act_Cour] AS 'SSt_Nr_Act_Cour', T3.[U_SSt_Nr_Act_CourQTY] AS 'SSt_Nr_Act_CourQTY',
  T3.[U_Fusing_foil] AS 'Fusing_foil', T3.[U_NO_Fabric_1] AS 'NoFabric1',
 T3.[U_NoSwing_tag] AS 'NoSwing_tag', T3.[U_No_Closure] AS 'No_Closure', T3.[U_No_GENERALPRINT] AS 'No_GENERALPRINT', T3.[U_No_LiningTrimming] AS 'No_LiningTrimming', T3.[U_No_Thread] AS 'No Thread', T3.[U_No_buckle] AS 'No_buckle', T3.[U_No_button] AS 'No_button', T3.[U_No_carton_pkg] AS 'No_carton_pkg', T3.[U_No_exposing1] AS 'No_exposing1', T3.[U_No_label] AS 'No_label', T3.[U_No_pigment1] AS 'No_pigment1', T3.[U_No_plasticol1] AS 'No_plasticol1', T3.[U_No_polybag] AS 'No_polybag', T3.[U_No_zip] AS 'No_zip', T3.[SlpCode] AS 'Sales Employee', T3.[DocStatus] AS 'Document Status', T3.[U_Red_clock] AS 'Red Clock', T3.[U_Green_Flag] AS 'Green Flag', T2.[U_PPS_photo_datereq] AS 'Sample Photo Req', T3.[U_PPSPhotoETA] AS 'Sample Photo ETA', T3.[U_PP_submit] AS 'Photo Sample Submit', T3. [U_PP_approved] AS 'Photo Sample Approved', 
 T2.[U_PPSsample_reqdate] AS 'Physical Sample Req', T3.[U_PPSSampleETA] AS 'Physical Sample ETA', 
 T3.[U_PPPhysical_submit] AS 'Physical Sample Submit', T3. [U_PPPhysical_apprvd] AS 'Physical Sample Approved',
  T2.[Dscription] AS 'Description' 
 FROM  [dbo].[OITB] T0  INNER  JOIN [dbo].[OITM] T1  ON  T1.[ItmsGrpCod] = T0.[ItmsGrpCod] 
   INNER  JOIN [dbo].[RDR1] T2  ON  T2.[ItemCode] = T1.[ItemCode]  AND  T2.[ItemCode] = T1.[ItemCode] 
     INNER  JOIN [dbo].[ORDR] T3  ON  T3.[DocEntry] = T2.[DocEntry]
      WHERE T3.[DocStatus] = (N'O' )  

 group by T3.[DocNum] , T3.[CardCode] , T3.[CardName] , T2.[ItemCode],  
T2.[Quantity] , T2.[U_ALP_DateETA] , T3.[DocDueDate] , T3.[DocDate], T3.[U_DateArtwkappCUST] ,
 T3.[U_DateProdctionApp] , T3.[U_ETA_UK_arrival], T3.[U_Cutting_start] , T3.[U_CuttingStartACT],
  T3.[U_CuttingEndACT] , T3.[U_Print_start] , T3.[U_PrintStartACT], T3.[U_PrintEndACT] , 
T3.[U_Ex_factory], T3.[U_ExFactoryACT] ,
 T2.[U_ALP_DespatchMethod] , T3.[U_ETAUKArrivalACT] ,
 T3.[U_ALP_TrackRef] ,t3.U_sst_NR_ACT,t3.u_SST_Nr_Act_Air,t3.u_sst_Nr_ACT_BA,t3.u_sst_Nr_Act_sea,
 t3.u_sst_Nr_Act_cour,T3.[U_Fusing_foil] , T3.[U_NO_Fabric_1] ,
 T3.[U_NoSwing_tag] , T3.[U_No_Closure] , T3.[U_No_GENERALPRINT] , T3.[U_No_LiningTrimming] , 
 T3.[U_No_Thread] , T3.[U_No_buckle] , T3.[U_No_button] ,
  T3.[U_No_carton_pkg] , T3.[U_No_exposing1] ,
   T3.[U_No_label] , T3.[U_No_pigment1] ,
    T3.[U_No_plasticol1] , T3.[U_No_polybag] ,
     T3.[U_No_zip] , T3.[SlpCode] , T3.[DocStatus] ,
      T3.[U_Red_clock] , T3.[U_Green_Flag] , 
      T2.[U_PPS_photo_datereq] , T3.[U_PPSPhotoETA] , 
      T3.[U_PP_submit] , T3. [U_PP_approved] , 
 T2.[U_PPSsample_reqdate] , T3.[U_PPSSampleETA] , 
 T3.[U_PPPhysical_submit] , T3. [U_PPPhysical_apprvd] ,
  T2.[Dscription],T3.[U_SST_Nr_Act_AirQTY],T3.U_SST_Nr_Act_BAQTY,T3.U_SSt_Nr_Act_CourQTY,T3.U_SST_Nr_Act_SeaQTY