To determine the sum of angle 6 and angle 8, we need to analyze their relationships given that \( M \) and \( N \) are parallel lines and angle 1 is \( 135^\circ \).
In this scenario, we can use the properties of angles formed by a transversal intersecting parallel lines:
- Corresponding Angles: Corresponding angles are equal.
- Alternate Interior Angles: Alternate interior angles are equal.
- Consecutive Interior Angles (Same-Side Interior Angles): These angles are supplementary (they add up to \( 180^\circ \)).
If we designate the angles as follows based on their positions:
- Angle 1 is given as \( 135^\circ \).
Here's the relationship between the angles:
- Angle 1 (which is \( 135^\circ \)) and angle 8 are on the same side of the transversal and are supplementary.
- Therefore, angle 1 and angle 8 satisfy the relationship: \[ \text{angle 1} + \text{angle 8} = 180^\circ \] Substituting \( 135^\circ \) for angle 1: \[ 135^\circ + \text{angle 8} = 180^\circ \] Solving for angle 8 gives: \[ \text{angle 8} = 180^\circ - 135^\circ = 45^\circ \]
Since angle 6 is vertically opposite to angle 8 (because of the transversal crossings), then:
- Angle 6 is equal to angle 8: \[ \text{angle 6} = 45^\circ \]
Now, we can find the sum of angle 6 and angle 8: \[ \text{Sum of angle 6 and angle 8} = \text{angle 6} + \text{angle 8} = 45^\circ + 45^\circ = 90^\circ. \]
Thus, the sum of angle 6 and angle 8 is \( \boxed{90^\circ} \).