The missing number is 26.
The table shows a sequence of numbers that increase by 4, then 2, then 4, and so on.
The first row starts at 2 and increases by 4 to get to 6.
The second row starts at 6 and increases by 2 to get to 8.
The third row starts at 8 and increases by 4 to get to 12.
However, there is no 12 in the table. Instead, there is a 19. This is because the pattern starts over again at 10, but this time the numbers increase by 9 instead of 4.
So, the fourth row starts at 10 and increases by 9 to get to 19.
The fifth row starts at 19 and increases by 2 to get to 21.
Therefore, the missing number in the fourth row is 26, because 10 + 4 + 4 + 4 + 4 = 26.