28. You do 2x + (4x + 12) = 180. That gets you 6x + 12 = 180. Minus the 12 from both sides. 6x = 168. Divide both sides by 6 then you get 28.
Answer:
2x + 2x + (4x + 12) + (4x + 12) = 360
12x + 24 = 360
12x = 360 - 24
12x = 336
x = 336/12 = 28
