Answer:
The answer is 2.
Explanation:
If ABCD is a parallelogram and it is a square, you need to have equal value for ell of the sides, this is how it would look like:
A-2x+8--B
6x
C----------D
So to get the value of x you just have to equalize both terms:
6x=2x+8
You clear the X and you get the next equation:
6x-2x=8
4x=8
x=

x=2