please dijawab pake cara

Mapel : Matematika
Materi : Kesebangunan
Kelas : 9

Nilai AB
[tex] \frac{ab}{ad} = \frac{bc}{ed} \\ \\ \frac{ab}{20} = \frac{20}{5} \\ \\ 5ab = 400 \\ \\ ab = \frac{400}{5} \\ \\ ab = 80 \: cm[/tex]

========================== Jawaban ==========================

  AB          20
-------  =  -------
  20           5

5AB = 400

   AB = 80 cm (C)

Maaf kalau salah