The angle at the center is twice that at the circumference, that is how 220 was obtained because 2 x 110 = 220
Also, the sum of angles at the center equals 360
so that (6x +8) + (60) + 220 = 360
6x + 8 + 60 + 220 = 360
6x + 288 = 360
6x = 360 -288
6x = 72
Dividing both sides by 6
x = 72/6
x = 12
