Answer:
x = 8
Step-by-step explanation:
Measure of unknown angle 'y' = 180° - 71° (linear pair of angles)
= 109°
Formula for the interior angle of a polygon = (n - 2) × 180°
Here n = number of sides of the polygon
Therefore, sum of the interior angles of the given polygon = (4 - 2) × 180°
= 360°
(10x + 6) + (13x - 2) + (8x - 1) + y = 360°
(10x + 13x + 8x) + (6 - 2 - 1) + 109 = 360
31x + 3 + 109 = 360
31x + 112 = 360
31x = 360 - 112
31x = 248
x = 8
