Answer:
x = 4
Step-by-step explanation:
The angle next to (adjacent to) 19x + 3 is 180 degrees less (19x + 3):
180 - (19x + 3)
and the three interior angles of the triangle must sum up to 180 degrees:
11x - 2 + 180 - 19x - 3 + 9x + 1 = 180, or
11x - 2 - 19x - 3 + 9x + 1 = 0
Combining like terms, we get:
x = 4
