Step-by-step explanation:
If -40x + 18, -20x + 3 and 15x + 92 angles of a triangle.
Then -40x + 18 + -20x + 3 + 15x + 92 = 180°, by angle sum property of a triangle
-40x + 18° + -20x + 3° + 15x + 92° = 180°
(-40x -20x + 15x) + (18° + 3° + 92°) = 180°
(-60x + 15x) + 113° = 180°
45x = 180° - 113°
45x = 67°
x = 67°/45
x = 1.48
x = 1.5(rounding off)