tolong kerjain no 5b dan no 6b jelaskan cara menentukan besar2 sudut pada setiap gambar ?

5b. 2x + 10° + 30° = 180°
2x + 40° = 180°
2x = 180° - 40°
2x = 140°
x = 140°/2
x = 70° → Terbukti

6b. 8x + 5° + 135° = 180°
8x + 140° = 180°
8x = 180° - 140°
8x = 40°
x = 40°/8
x = 5° → terbukti