Answer:
x = 20
3x - 2 = 58°
Explanation:
Sum of exterior angles of any polygon = 360°
90 + 70 + 3x - 2 + 4x - 10 + 3x + 12 = 360
90 + 70 - 2 - 10 + 12 + 3x + 4x + 3x = 360
Combine like terms. Like terms have same variable with same power. Add or subtract the co-efficient of the like terms.
160 + 10x = 360
Subtract 160 from both sides,
10x = 360 - 160
10x = 200
Divide both sides by 10,
x = 200 ÷ 10

3x - 2 = 3*20 - 2
= 60 - 2
= 58°