Answer:
x = 14
Step-by-step explanation:
The angles form a straight line which makes them add to 180 degrees
4x+ 8x+12 =180
Combine like terms
12x+12 =180
Subtract 12 from each side
12x+12-12 = 180-12
12x=168
Divide each side by 12
12x/12 =168/12
x =14
