Question

what is $m\angle 1$?
(there is a triangle with angles 53° and 75°, and angle 1 is an exterior angle related to the triangle)
$m\angle 1 = \square^\circ$

Explanation:

Step1: Find triangle's third angle

Let the third interior angle be $x$.
$x = 180^\circ - 53^\circ - 75^\circ = 52^\circ$

Step2: Relate to $\angle1$ (supplementary)

$\angle1$ and $x$ form a straight angle.
$m\angle1 = 180^\circ - 52^\circ$

Answer:

$128$