Answer:
The answer is angle 4.
Explanation:
Complimentary angles add up to 90°. So when it says what is the complimentary angle to angle 5, they want to know which angle will add up to 90° along with angle 5. We know that angles 1 and 3 are congruent and that angle 2 and angles 4+5 are congruent. Therefore angles 4 and 5 must add up to 90°.