We know that the two angles are opposite and therefore are equal, so we can set them equal to each other and solve for x:
3x + 50 = 6x - 10
Adding 10 to both sides, we get:
3x + 60 = 6x
Subtracting 3x from both sides, we get:
60 = 3x
Dividing both sides by 3, we get:
x = 20
Therefore, the value of x is 20.