The relationship between angle 5 and angle 1 is that they are alternate exterior angles.
When a transversal intersects two parallel lines, the angles that are located on opposite sides of the transversal and outside the two lines are known as alternate exterior angles. In this case, angle 5 (which is on the upper line N) is located outside the parallel lines, and angle 1 (which is on the upper line M) is also positioned outside but on the opposite side of the transversal.