Answer:
I think that 18
Explanation:
72/4 - why 4? square= 4 sides
=18
and why a division? the perimeter is all sides added
18+18+18+18 = 72
It's says "is no less", that mean that can be 72 or a bigger number, like 100 or less so you can try with others numbers
srry if i didn't help