Answer: x = 6
Explanation:
m∠2 and the unknown angle are congruent since their opposite sides are also congruent.
m∠2 = 12x - 2
Unknown angle = y = 12x - 2
m∠2 + y + m∠40° = 180° since they are angles of a triangle
12x - 2 + 12x - 2 + 40 = 180
24x - 4 + 40 = 180
24x + 36 = 180
Subtract 36 from both sides
24x = 144
Divide both sides by 24
x = 6
I hope I helped!