1. The problem asks for the complement of an angle measured in degrees, denoted as $a$. 2. The complement of an angle is defined as the amount by which the angle must increase to reach 90 degrees. 3. The formula for the complement of an angle $a$ is: $$\text{complement} = 90 - a$$ 4. This means if you have an angle $a$, its complement is what you add to $a$ to get 90 degrees. 5. For example, if $a = 30$, then the complement is $90 - 30 = 60$ degrees. 6. Therefore, the complement of $a$ degrees is simply $90 - a$ degrees.