Remark
The measure of the two angles add to 180. That permits you to solve for x.
Givens
1. Supllementary angles add to 180o
2. A = 2x
3. B = x -6
Equation
A + B = 180
2x + x - 6 = 180
Solution
2x + x - 6 = 180 Combine like terms
3x - 6 = 180 Add 6 to both sides
3x = 180 + 6
3x = 186 Divide by 3
x = 186/3
x = 62
Answer
A = 2x
A = 124
B = x - 6
B = 62 - 6
B = 56
I'm sorry to say that I'm not getting any of them. The intended answer is likely B which I would try first. A and D do not add to 180. C does add to 180 but it looks like the answer was derived by taking x to be one of the angles and then the supplement would be 180 - 62 = 118.
A D and C are all incorrect. B is not either, but it is the closest.