Respuesta :

mwfelix8888

Answer:

10cm

Step-by-step explanation:

Since ABC and DEF are similar, the ratio of their side is always the same.

The ratio here is:

DF/AC = 6/4 = 1.5

Therefore, it means that BC x 1.5 = EF

So:

BC x 1.5 = 15

BC = 15 / 1.5 = 10cm.