Answer:
2
Explanation:
I don't think you are asked to prove that these triangles are similar. The diagram leads you to believe that they are. The easiest way to solve this is to take 2 corresponding lines and compare them.
So how do you get from FE to BA
BA / FE = 6/3
BA = 6
FE = 3
BA / FE = 6/3
BA / FE = 2
The scale factor is 2