Question

find the measure of the unknown angle (?) given an exterior angle of 155° and an interior angle of 60° in a triangle-related figure.

Explanation:

Step1: Find interior angle of triangle

The 155° angle is supplementary to the adjacent triangle interior angle.
$180^\circ - 155^\circ = 25^\circ$

Step2: Calculate unknown interior angle

The sum of angles in a triangle is $180^\circ$. The unknown angle is supplementary to the triangle's missing angle. First find the triangle's missing angle:
$180^\circ - 25^\circ - 60^\circ = 95^\circ$

Step3: Find the exterior unknown angle

The unknown angle is supplementary to the 95° triangle angle.
$180^\circ - 95^\circ = 85^\circ$

Answer:

$85^\circ$