yang tau no 12 tolong isi dong pakek cara nya makasih

12.
→
a / c = (a + b) / (c + d)

→
a / (a + b) = c / (c + d)

→
a / e = (a + b) / f

→
c / e = (c + d) / f

→ e / f = c / (c + d) { Jawaban B }