Answer:
x = 40
Explanation:
the sum of the 3 angles in a triangle is 180°
sum the 3 angles, equate to 180 and solve for x
2x - 10 + 2x - 30 + 2x - 20 = 180 ( simplify left side )
6x - 60 = 180 ( add 60 to both sides )
6x = 240 ( divide both sides by 6 )
x = 40