The image shows a triangle with angles 50°, 100°, and $x$ (the unknown angle we need to find). The sum of all interior angles of a triangle is always 180°.

To find the unknown angle $x$:

$x = 180^\circ - 50^\circ - 100^\circ$

$x = 180^\circ - 150^\circ = 30^\circ$

Thus, the value of $x$ is $30^\circ$. The correct answer is B. 30°.

Would you like more details or have any further questions?

Here are some related questions to expand your understanding:

1. How do we calculate the exterior angle of a triangle?
2. What is the sum of the angles in a quadrilateral?
3. What happens to the angles in an equilateral triangle?
4. How would the solution change if this were an obtuse triangle?
5. Can a triangle have more than one obtuse angle?

Tip: Always remember that the sum of interior angles in any triangle is 180°.