The image shows a diagram with angles. Solve for x and state the definition of angles at a point.

$$x = 180^\circ - 100^\circ$$ $$x = 80^\circ$$

The value of $x$ is \boxed{\text{80^\circ}}.

2. Definition of angles at a point:

Angles which meet at a point: The sum of all angles around a point is \boxed{\text{360^\circ}}.