Answer:
20°
Step-by-step explanation:
The sum of all three angles combined is 90°. You can see this by the square at the corner. This means that you have to add all of the angles together and set it equal to 90° to solve for x.
x° + 2x° + (x + 10)° = 90°
3x° + (x + 10)° = 90°
4x° + 10° = 90°
4x° = 80°
x = 20°
