Here, sum of last column = 0 + 11 + 7 + 12
Solving for last row,
x + 2 + 1 + 12 = 30
∴ x = 15
Solving for first column,
x + 8 + 4 + 15 = 30
∴ x = 3
Solving for first row,
3 + 14 + x + 0 =30
∴ x = 13
Solving for second row,
8 + x + 6 + 11 = 30
∴ x = 5
Solving for second column,
14 + 5 + x + 2 = 30
∴ x = 9
Solving for third column,
13 + 6 + x + 1 = 30
∴ x = 10