Complimentary angles are those that add up to 90 degrees. Angle 1 + Angle 2 = 90°
since the angle given is 23° we subtract it from 90° to find the other. let's say angle 2 is X.
23° + X = 90°
(subratct 23 from both sides)
23°-23° + X = 90° - 23°
X = 67°
That's it! 67° is the answer. Hope that helps, if not just ask!