jawablah pertanyaan berikut...

<a + <b + <c = 180°
x° + 3x + 60 = 180
4x + 60 = 180
4x = 180 - 60
4x = 120
x = 120/4
= 30°
<a = x°
= 30°
Jawabannya b. 30°

caranya =
3x = 60
 x = 60/3
    = jawab sendiri