Question

which angle is complementary to $\angle afb$?

Explanation:

Step1: Recall complementary angle definition

Complementary angles sum to $90^\circ$.

Step2: Identify right angle at F

$\angle BFC$ is a right angle ($90^\circ$), so $\angle AFB + \angle AFC = 90^\circ$.

Step3: Verify other adjacent angles

$\angle AFB + \angle AFE$ does not equal $90^\circ$, as lines DB and EC are perpendicular, so only $\angle AFC$ adds with $\angle AFB$ to make $90^\circ$.

Answer:

$\angle AFC$