Find the missing number?

A. 6

B. 20

C. 8

D. 17

Answer: Option C

Solution(By Examveda Team)

In each grid, working in columns, add the top and bottom numbers together, and put this sum in the centre square in the grid underneath the original (for the top grids), or the grid above (for the lower grids). So,

5 + x = 13
x = 8.