The letters in the first row follow the sequence +5, +7.
The letters in the second row follow the sequence +6, +8. In the third row, the first letter G moves 7 steps forward to give the second letter N. Clearly, the missing letter will be 9 steps ahead of N i.e. W.
The numbers in the first row form a series 12, 22, 32. So, missing number in the first row = 42 = 16. The number in the second row from the series, 1, 2, 3, 4. The number in the third row from the series 2, 4, 6. So, missing number in the third row = 6 + 2 = 8.