Answer:
15 DEGREES
Step-by-step explanation:
OK SO BASICALLY, USING THE EXTERIOR ANGLES THEOREM, YOU FIND THAT 9x = 5x + something. That something is 4x so:
9x = 5x + 4x
THEN YOU FIND THAT 8x = 5x + something. That something is 3x so:
8x = 5x + 3x
4x and 3x and 5x are the interior angles of the triangle (ABC)
Then you use triangle theorem and get 4x + 3x + 5x = 180
Then: 12x = 180 and so you get x = 15
