Step-1: Understanding the Diagram
Since we can see the "square" at the bottom left corner of the angle, the square indicates that the angle is a right angle (which measures 90°).
We can also see three smaller angles forming the right angle. Therefore, the sum of the measure of the smaller angles = 90°.
According to the diagram, the measures of the smaller angles are x°, 2x°, and (x + 10)° respectively. Then we get the following equation:

Step-2: Solving the equation obtained in step-1
Here, we had the equation:






Therefore, the value of x, in the diagram provided, is 20.