Verified answer

Пусть ∠kn = x, тогда ∠mk = 8x. Сумма смежных углов равна 180°

8x + x = 180

9x = 180

x = 180 : 9

x = 20

∠kn = x = 20°

∠mk = 8x = 20 * 8 = 160°