Answer:
8) interior angle = 160
9) x = 20
Step-by-step explanation:
8)
18-gon has 18 sides
The formula for sum of interior angles for an 18-gon is:
(18x180)-360 = 2880 degrees
2880 degrees / 18 angles = 160 degrees
9)
exterior angles = 360 degrees
360 = (3x-2)+(x+8)+(4x+9)+(2x-1)+(3x)+(4x+6)
360 = 3x-2+x+8+4x+9+2x-1+3x+4x+6
360 = 17x+20
17x = 340
x = 20 degrees
