3) f)

The sum of angles in a triangle is 180°. In the triangle formed by points d, e, and the center, two angles are 12° and 24°. The third angle at the center is 180° - (12° + 24°) = 180° - 36° = 144°. The angle 'f' is subtended by the arc corresponding to this central angle. So, f = 144° / 2 = 72°.