It's simple. I won't draw a picture for you. Let AD and BF intersect at point P, ∠ACB=, ∠ AED = 105, so ∠APC=95 (the external angle of one angle is equal to the sum of two internal angles). Therefore, ∠DPF=95 degrees (equal vertex angles).

Therefore, ∠DFB=60 (the sum of the interior angles of the triangle is 180).

Not difficult. Take a good look and you should understand.