The correct relationship between angle 5 and angle 1 is that they are alternate exterior angles.
When two parallel lines (M and N) are cut by a transversal (the inclined line), the angles that lie outside the parallel lines and are on opposite sides of the transversal are considered alternate exterior angles. In this case, angle 1 is located outside line M, and angle 5 is located outside line N, making them alternate exterior angles.