tolong bantu jawab no 21,22 menggunakan caranya

Garis dan Sudut

No.21
a : b = 5 : 4
a = 5X
b = 4X

a + b = 90°
5X + 4X = 90
9X = 90
X = 90/9
X = 10

a = 5X
a = 5 x 10
a = 50° (D).

No.22
<APB + <BPC = 180°
7X - 10 + X + 30 = 180
8X + 20 = 180
8X = 180 - 20
8X = 160
X = 160/8
X = 20

Pelurus <APB = <BPC
= X + 30
= 20 + 30
= 50° (B).

*semoga membantu. sukses selalu ^_^