I think it would be 1 5/4 that would be your answer
Answer: 
Work Shown:

This can be rewritten into 
15 gggggggggggggggggggggg
Answer:

Step-by-step explanation:
Scale Factor = 5
Also,
B'C' = 24 feet
Since both are squares so both have all sides equal.
Sqaure A'B'C'D' is dilated by a scale factor of 5
So,
AB = BC = CD = DA = 24/5 = 4.8 ft.