In this diagram, there’s a right angle at the bottom left corner, and the angle marked as $18^\circ$ is adjacent to angle $x$. Since the angles in a right triangle sum up to $90^\circ$, we can find $x$ as follows:

$x = 90^\circ - 18^\circ = 72^\circ$

So, $x = 72^\circ$.

Would you like a deeper explanation or have any questions about this solution?

1. What is the sum of angles in a triangle?
2. How do complementary angles work in right triangles?
3. Why is subtracting from 90 degrees essential here?
4. How do trigonometric functions apply to this type of triangle?
5. Can this approach be applied to all right-angle triangles?

Tip: Remember, the sum of angles in any triangle is always $180^\circ$.