gaess tolong dong,,, gk ngerti neh caranya sekalian ya,,, thanks

Bab Garis dan Sudut

a. Buat persamaannya dulu
180° - 1/3 ∠a = 160°
180° - 160° = 1/3 ∠a
1/3 ∠a = 20°
∠a = 20° × 3
∠a = 60°

b. 2 × ∠a + 180 - ∠a + 2 × (90 - ∠a)
= 2 (60) + 180 - 60 + 2 (90 - 60)
= 120 + 120 + 60
= 300°