Uchburchaklar o'xshashligi

Uchburchaklar o'xshashligi: $\angle BAC = 72^\circ$; $\angle ABC = 64^\circ$; $\angle MKN = \gamma = ?$ Uchburchaklar o'xshashligi: $\angle NMK = 84^\circ$; $\angle NKM = 48^\circ$; $\angle ABC = \beta = ?$ Uchburchaklar o'xshashligi: $AB = 10$; $BC = 15$; $AC = 20$; $MN = 4$; $NK = y$; $MK = x$; $x + y = ?$ Uchburchaklar o'xshashligi: $AB = 15$; $BC = 20$; $AC = 30$; $MN = 9$; $NK = y$; $MK = x$; $x - y = ?$ Uchburchaklar o'xshashligi: $AB = 12$; $BC = y$; $AC = 18$; $MN = 4$; $NK = 5$; $MK = x$; $y + 2x = ?$ $DE\parallel BC$; $AD = 6$; $AE = 5$; $BD = 9$; $EC = x = ?$