Answer:
39
Step-by-step explanation:
Since a square has 4 equal sides, it's safe to do [tex]\frac{52}{4}[/tex] to get each side length (each side is 13 mm).
Dilating a side means you're multiplying it by the scale factor. This means that you're doing [tex]13*3[/tex] to each side (each side is 39 mm).
