Answer:
12
Step-by-step explanation:
10x-11+3x-2+3x+1=180
16x-12=180
16x=192
x=12
The sum of three angles is 180°
(3x + 1) + (3x-2) + (10x -11) = 180°
16x -12 = 180
16x = 192
x = 12
