Complementary angles are angles that add up to 90 degrees.
We can see that angle 2 and angle 1 add up to 90 degrees (as the combination of angle 2, angle 1 and the right angle given are supplementary.)
Angle 1 on the other hand, is equal to angle 4 (opposite angles)
Therefore, we can conclude that angle 2 and angle 4 are complementary.