Answer:
x=54
Step-by-step explanation:
easy
180 is a triangle
so
exterior+interior=180
so 180-123
57
now add all up to 180
180=57+x+69
9514 1404 393
54
The sum of the interior angles marked is the same as the marked exterior angle. Then the unknown is the difference of the known angles:
x° = 123° -69°
x° = 54°
