Answer:
EF = 12 cm
Step-by-step explanation:
If the triangles are similar, that means that their lengths are proportional. So, from what we are given, for every 5 cm ∆ABC has, ∆DEF has 4.
So, 5/4 = 15/EF.
5EF = 4*15
EF = 4 * 3
