pleesss tolong dibantu pakae cara ya...

<AOC + <COB = 90°
(6x + 4)° + (5x + 9)° = 90°
(11x + 13)° = 90°
11x = (90-13)°
11x = 77°
x = 7°

x = 7° disubtitusi ke <AOC
= (6x +4)°
= (42+2)°
= 44°

semoga membantu