Answer
$78\frac{3}{4}°$
Work Step by Step
Two angles are complementary if the sum of their measures is 90°.
The complement of a $11\frac{1}{4}°$ angle is an angle whose measure is $90°-11\frac{1}{4}° = 78\frac{3}{4}° $
To check, notice that $11\frac{1}{4}° + 78\frac{3}{4}°= 90°$.
