In the diagram, PQ and RS are straight lines. What is the value of y? In the diagram, KL is a straight line. What is the size of angle x? What is the size of angle x in the diagram?

Subtract $2y$ from both sides.

$$25 = y - 5$$

$$25 + 5 = y$$ $$y = 30$$

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

One angle is $90^\circ$ (indicated by the square symbol), and another is $55^\circ$. The third angle in this triangle is $180^\circ - 90^\circ - 55^\circ$.

$$180^\circ - 90^\circ - 55^\circ = 35^\circ$$

Vertically opposite angles are equal.

$$x = 35$$

The size of angle $x$ is $\boxed{\text{35}^\circ}$.

The exterior angle $30^\circ$ is equal to the sum of the two opposite interior angles, $x^\circ$ and $80^\circ$.

$$30^\circ = x^\circ + 80^\circ$$

Subtract $80^\circ$ from both sides.

$$x^\circ = 30^\circ - 80^\circ$$ $$x^\circ = -50^\circ$$

This result is not possible for an angle in a standard geometric context. Let's re-interpret the diagram.

Alternative Interpretation for c):
It is more likely that the $30^\circ$ angle is an interior angle of the triangle, and the $80^\circ$ angle is an exterior angle. Or, the $80^\circ$ is an interior angle, and the $30^\circ$ is an interior angle. Given the placement, it's common for the angle at the intersection of the two lines to be an interior angle of the triangle formed by the base.

Let's assume the $80^\circ$ is an interior angle of the triangle, and the $30^\circ$ is an exterior angle to the triangle at the vertex B.
If $30^\circ$ is an exterior angle at B, then the interior angle at B is $180^\circ - 30^\circ = 150^\circ$.
Then $x + 150^\circ + 80^\circ = 180^\circ \implies x = -50^\circ$. This is still not possible.

Let's assume the $80^\circ$ is an interior angle of the triangle, and the $30^\circ$ is also an interior angle of the triangle.
The sum of angles in a triangle is $180^\circ$.

$$x^\circ + 110^\circ = 180^\circ$$ $$x^\circ = 180^\circ - 110^\circ$$ $$x^\circ = 70^\circ$$

This interpretation yields a positive angle and is consistent with typical geometry problems. The way the $30^\circ$ is drawn, it's at the base, which often implies it's an interior angle.

The size of angle $x$ is $\boxed{\text{70}^\circ}$.