jwb dong kak pliss dengan cara

nomor 8
EF = (DE x AB)+(AE x CD)/AE+DE
EF = (5 x 20)+(3 x 12)/3+5
EF = 100+36/8
EF = 136/8
EF = 17 cm

nomor 9
DE/AB = CE/CB
DE/15 = 6/6+4
DE/15 = 6/10
10DE = 6 x 15
10DE = 90
DE = 90/10
DE = 9 cm

*semoga membantu. sukses selalu ^_^