It should be simple as below
SELECT [INWARD RG].MD
,[INWARD RG].UNIT
,[SumOfConverted Qty]+SumOfPurchase1+[SumOfSite Return Qty] As STOCK
,[INWARD RG].[SumOfConverted Qty]
,[INWARD RG].SumOfPurchase1
,[INWARD RG].[SumOfSite Return Qty]
FROM [INWARD RG];