Answer:
12x=180 -30
x= 150/12
x= 12.5°
x = 12.5
Step-by-step explanation:
The 3 angles lie on a straight line and so sum to 180°, that is
x + 10 + 10x + x + 20 = 180, simplify
12x + 30 = 180 ( subtract 30 from both sides )
12x = 150 ( divide both sides by 12 )
