Since the other angle that right next to it, the same angle you equal both angles together.
4x = 68.
We want to get x by its self. There is a 4 with the x and they're multiplying. to get rid of 4 we need to the opposite of multiplying which is division on both sides of the equation.
4x = 68
/4 /4
4 divided by 4 is 1 and 68 divided by 4 is 17
x = 17 is the answer.
If you plug in x = 17 into 4x, it will be 68