Perhatikan gambar berikut.

4x+(2+126) = 180
4x + 128 = 180
4× = 180-128
4x = 52°
× = 52/4
x = 13°

2y+(12+126) = 180
2y + 138 = 180
2y = 180-138
2y = 42°
y = 42/2
y = 21°

Jadi x+y
= 13+21
= 34°