😛

You have all the answer in your code...

SELECT ComputerName AS [Computer Name]

, [Name] AS [Printer Name]

, SUM(BlackWhiteTotalCount) AS [Total B&W Pages]

, SUM(FullColorTotalCount) AS [Total Color Pages]

, SUM(BlackWhiteTotalCount) + SUM(FullColorTotalCount) AS [Total]

FROM [dbo].[db_name]

WHERE ComputerName LIKE 'ComputerName%'

GROUP BY [ComputerName], [Name]

Just add the two sums to get the final total...