tolong dijawab sama caranya ya makasih

a = 3x
b = 5x
d = 7x

→ Cara mencari x :

a + d = 180
3x + 7x = 180
10x = 180
x = 180 / 10
x = 18

→ Cara lain mencari x :

5x + c = 180

3x + 5x + 7x + c = 360
15x + c = 360

15x + c = 360
5x + c = 180
------------------ (-)
10x = 180
x = 180 / 10
x = 18

→ Cara mencari c :

c = 360 - 15x
c = 360 - 15 (18)
c = 360 - 270
c = 90

→ Cara lain mencari c :

c = 180 - 5x
c = 180 - 5(18)
c = 180 - 90
c = 90