bantuu ya...9 point guys.!! panjang foto???????

18/28 = pf/40
9/14 = pf/40
14 pf = 9 x 40
pf = 360/14
pf = 25,71 - 5
pf = 20,71

pf/40 = 15/28
pf =40.15/28=21,42 cm