Answer:
x = 9
Step-by-step explanation:
Theorem:
The measure of an exterior angle of triangle equals the sum of the measures of its two remote interior angles.
The angle measuring 12x + 14 is an exterior angle of the triangle.
The angles measuring 76 deg and 1 + 5x are its remote interior angles.
12x + 14 = 1 + 5x + 76
12x + 14 = 5x + 77
7x = 63
x = 9
