Easy.
When you combine all the angles of the triangle, the sum will be 180°.
Angle 1 is 30% of 180 which is 52. This means angle 1 is 54°.
Angle 2 is 25% of 180 which is 45. This means angle 2 is 45°.
The sum of all the angles is 180° so angle x + 54° + 45° = 180°.
To find x, subtract 54 from 180 to get 126. Then subtract 45 from 126 to get 81.
This means angle x is 81°.
The value of x is 81.