tolong......ada yg bisa gaa? jawabannya D bukan? help me onegaii

Kalo jawaban gue sih gini....

M = h'/h
M = 3/1
M = 3 x

S = f ( M +1) / M
S = 12 ( 3+1) / 3
S = 48 / 3
S = 16 cm

S = 16 - 12 = 4 cm

Jari2 kelengkungan = 2(f) = 2 (12) = 24 cm

Agar Bayangan sama besar = 24 - 4 = 20 cm