Tentukan nilai x° + y° + z° pada gambar di bawah ini.

Materi : garis dan sudut
Kelas : 7 SMP

12x + 108 = 180
12x = 180 - 108
12x = 72
x = 72/12
x = 6

56 + 5x + 2y = 180
56 + 5(6) + 2y = 180
56 + 30 + 2y = 180
2y = 180 - 56 - 30
2y = 94
y = 94/2
y = 47

4z + 12x + 56 = 180
4z + 12(6) + 56 = 180
4z + 72 + 56 = 180
4z = 180 - 72 - 56
4z = 52
z = 52/4
z = 13

x + y + z = 6 + 47 + 13
= 66