Answer:
x = 70
Explanation:
112°, y and z are the angles inside triangle.
112 + y + z = 180
y + z = 180 - 112
y + z = 68 (I)
{2x + y = 180
{2x + 12 + z = 180
2x + y = 2x + 12 + z
y = z + 12 (II)
Changing (II) in (I):
y + z = 68
z + 12 + z = 68
2z + 12 = 68
2z = 68 - 12
2z = 56
z = 28
y = z + 12
y = 28 + 12
y = 40
2x + y = 180
2x + 40 = 180
2x = 180 - 40
2x = 140
x = 70
I hope I've helped you.