The interior angles of a triangle will always add up to 180.
This means that 3x-14+3x+9+ angle BAC = 180
To find angle BAC, we have to subtract 103 from 180
(Because an exterior angle is equal to the sum of two opposite interior angles, and we know the exterior angle is 180 and one interior angle is 103)
This is 77
Now we solve 3x-14+3x+9+77 = 180
First, collect all like terms
6x+72=180
Next, subtract 72 from both sides
6x=108
Then, divide both sides by 6
X=18
Measure ABC is 3(18)+9
This is equal to 63
