Find the value of the missing angle.

The horizontal lines are parallel. We have a zigzag transversal intersecting these parallel lines.
The angles given are $x^\circ$, $78^\circ$, and $30^\circ$.

This rule states that for a zigzag line between two parallel lines, the sum of the angles pointing in one direction is equal to the sum of the angles pointing in the opposite direction.

• Angles pointing to the right: $x^\circ$ and $30^\circ$.
• Angles pointing to the left: $78^\circ$.

The value of $x$ is: