Answer:
30f + 20
Explanation:
A square has four sides, all of equal length. If we call that side length x, then the perimeter - the total length around the square - is 4x. To find the side length given the perimeter then, we can simply divide the perimeter by 4.
Our perimeter here is 120f + 80, and dividing each term by 4 gives us a side length of 30f + 20.