Answer:
slope =

Explanation:
Calculate the slope m using the slope formula
m =

with (x₁, y₁ ) = (- 8, 1) and (x₂, y₂ ) = (8, 9) ← 2 points on the green line
m =
=
=

Repeat with (x₁, y₁ ) = 0, 6) and (x₂, y₂ ) = (2, 7) ← 2 points on the blue line
m =
=

Since the slopes of both lines are equal, then the lines are parallel