1. **State the problem:** We have two triangles sharing a side. The left triangle is a right triangle with one angle of 65° and the right triangle has angles 50°, 80°, and an unknown angle $x$. We need to find $x$. 2. **Recall the triangle angle sum rule:** The sum of the interior angles in any triangle is always 180°. 3. **Analyze the right triangle on the right:** It has angles 50°, 80°, and $x$. Using the angle sum rule: $$50° + 80° + x = 180°$$ 4. **Solve for $x$:** $$x = 180° - 50° - 80°$$ $$x = 180° - 130°$$ $$x = 50°$$ 5. **Conclusion:** The unknown angle $x$ is 50°. This is consistent with the triangle angle sum property and the given angles.