What is the question mark?

After extensive guessing and checking, I found out that the first column and third column both had a sum of \(15\), which means that the second column had a sum of \(15\), also. 

\(15 - (8+1) = 15 - 9 = 6\), so \(? = 6\).

- Daisy

Daisy is correct !!!!...[ the sum of each row  is also 15...if the missing number is 6  ]