Answer:
x = 12
Step-by-step explanation:
Exterior Angle Theorem
The interior angles of a triangle sum to 180°. Angles on a straight line sum to 180°. Therefore, the exterior angle of a triangle is equal to the sum of the two non-adjacent interior angles of the triangle.
Given angles:
- [tex]\textsf{Exterior angle}: \quad m \angle BCD = 6x+2[/tex]
- [tex]\textsf{Non-adjacent interior angle}: \quad m \angle BAC= 3x+15[/tex]
- [tex]\textsf{Non-adjacent interior angle}: \quad m \angle ABC= 2x-1[/tex]
Apply the exterior angle theorem and solve for x:
[tex]\implies m \angle BCD=m \angle BAC+m \angle ABC[/tex]
[tex]\implies 6x+2=3x+15+2x-1[/tex]
[tex]\implies 6x+2=3x+2x+15-1[/tex]
[tex]\implies 6x+2=5x+14[/tex]
[tex]\implies 6x+2-5x=5x+14-5x[/tex]
[tex]\implies x+2=14[/tex]
[tex]\implies x+2-2=14-2[/tex]
[tex]\implies x=12[/tex]