We know that A=Q since the two shapes are congruent.
x - 10 = 2x - 30
Flip
2x - 30 = x -10
Subtract x from both sides
x - 30 = -10
Add 30 to both sides
x = 20
Plug it in into any of the two equations and you get 10
The answer is the first choice.
Have an awesome day! :)
