tolong jawab no 4 dan 5 dengan cara!!!

Kesebangunan

4.
20/a = 15/30
a = (20)(30)/15
a = 40

15/30 = 12/b
b = 12(30)/15
b = 24

20/c = (20+15)/60
c = (20)(60)/(35)
c = 34,29

(20+15)/60 = (20+15+12)/(d)
d = 60 (20+15+12)/(20+15)
d = 60(47)/(35) = 80.57

5.
2/x = 4/6
x = 2(6)/4 = 12/4 = 3
.
6/y = x / 4
6/y = 3/4
y = (6)(4)/(3)
y = 12