Question

What number goes in the missing space?

Answer 1

Find the pattern. 
The numbers are doubled: 8*2=16 16*2=32
Therefore the number in the missing spot would be 10*2 or 40/2
which equals 20.

Hope this helps! 

Answer 2

20 goes in the missing space.

In each example, the number in the top right equals the number in the top left times 2.

4*2=8
6*12=12
10*2=20