Ini gimana ya saya lupa tolong jawab secepatnya dgn caranya..

180° - 60° - 2x = 180° - (4x - 10°)
180° - 60° - 2x = 180° - 4x + 10°
120° - 2x = 190° - 4x
4x - 2x = 190° - 120°
2x = 70°
x = 70°/2
x = 35°

● ∠ABC = 180° - 60° - 2x
= 180° - 60° - 2(35°)
= 180° - 60° - 70°
= 50°

Atau:

● ∠ABC = 180° - (4x - 10°)
= 180° - 4x + 10°
= 180° - 4(35°) + 10°
= 180° - 140° + 10°
= 50°