Hello there!
On those type of angles, the angles that are facing each other is equal to another.
So you can set up the equation like this :
10x + 1 = 12x - 5
-2x = -6
x = 3
So the answer is x = 3.
In some problems, you have to find the angle.
Then you just simply substitute 3 into x.
10x + 1
10(3) + 1
30 + 1
31
12x - 5
12(3) - 5
36 - 5
31
The angles are 31° and 31°.
Hope this helped! :)