Answer:
x = 30
Explanation:
you can find it by vertical opposite angle which is their non adjecent angle are equal.
2x- 30 = 30
2x = 30 + 30 ..... take 30 to the left it change sighn
2x /2 = 60 / 2 ..... divided both side by 3
x = 30 ..... so the unknown no. is 30