Kak nomor 12 beserta caranya

3x + 2x - 10 = 180°
5x = 180 + 10
5x = 190
x = 190 : 5
x = 38

BDC = 2x - 10
BDC = 2(38) - 10
BDC = 76 - 10
BDC = 66°
b. 66°

Semoga membantu, kalau bisa jadi brainliest answer makasih :)