23. ME || NF, ∠EKF — ?

Given that ME || NF. The sum of angles in quadrilateral equals 360. Since the sum of two other angles are $$50^{\circ}$$ and $$30^{\circ}$$ then two other angles are 180 -50=130 and 180 - 30 = 150. Then $$\angle EKF = 360 - (130+150) = 360-280 = 80^{\circ}$$. The angle EKF = 180-80 = 100^{\circ} \angle EKF + angle 50 + angle 30 = 180 angle EKF = 180-80=100 **Answer: 100°**