Answer:
b
Step-by-step explanation:
The exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.
∠ 1 is an exterior angle of the triangle , then
∠ 1 = 30° + 39° = 69°
option b: 69°
the sum of the interior angles of a triangle is 180c.
that is, 39 + 30 + x = 180
x = 180 - 39 - 30
x = 111°
∠ 1 + x = 180° [ straight line angles ]
∠1 + 111° = 180°
∠1 = 180 - 111 = 69°
