In the diagram below X is

The diagram shows a triangle with sides AB = 5 cm, BC = 5 cm, and AC = $x$ cm. Sides AB and BC have double tick marks, indicating they are equal in length. Side AC has a single tick mark. In basic geometry problems where a specific value for $x$ is expected without additional information (like angles), different tick marks on all sides often imply that all sides are equal, making it an equilateral triangle. We will proceed with this common interpretation to find a unique value for $x$.

If the triangle is equilateral, all its sides are equal in length.
Therefore, $AC = AB = BC$.

The value of $x$ is $\boxed{\text{5 cm}}$.

The diagram shows a large right-angled triangle. The square symbol indicates a $90^\circ$ angle at the bottom left vertex. The angle at the top vertex is split into two parts: $45^\circ$ and $30^\circ$. The angle at the bottom right vertex is $x$.
The total angle at the top vertex is $45^\circ + 30^\circ = 75^\circ$.

The sum of the interior angles in any triangle is $180^\circ$.

The value of $x$ is $\boxed{\text{15}}$.

The diagram shows a right-angled triangle. One angle is $x^\circ$, another is $60^\circ$, and the third angle is $90^\circ$ (indicated by the square symbol).

The sum of the interior angles in any triangle is $180^\circ$.

The value of $x$ is $\boxed{\text{30}}$.