tolong no. 20 dong dgn cara kerjanya...

Besar sudut suatu segitiga apabila ditotalkan = 180 derajat

180 = 5x + 5 + 60 + 3x - 5
180 = 8x + 60
180 - 60 = 8x
120 = 8x
x = 120 : 8 = 15

total sudut segitiga = 180°
60 + 5x + 5 + 3x - 5 = 180°
60 + 5x + 3x + 5 - 5 = 180°
60 + 8x = 180°
8x = 180 - 60
8x = 120
x = 120 ÷ 8
x= 15

semoga membantu :)