nilai x tambah y + z pada gambar berikut adalah

7x + 40° = 180°
7x = 180° - 40°
7x = 140°
x = 140°/7°
= 20
80° + 2y = 7x
80° + 2y = 7×20°
80° + 2y = 140°
2y = 140° - 80°
2y = 60°
y = 60°/2°
= 30
2y + 4z + 40° = 180°
(2×30)° + 4z + 40° = 180°
60° + 4z + 40° = 180°
100° + 4z = 180°
4z = 180° - 100°
4z = 80°
z = 80°/4°
= 20

Nilai x + y + z pada gambar itu adalah
20 + 30 + 20 = 70