800 square feet equals X linear feet?

Answer 1

Square feet measure area and linear feet measures distance. There is not way to change area into distance.
To help you see this, think of a 10x10 square. The area is 100 square units. How can we change that into linear units? We could look at the sides and not each was 10 units, but there are other ways to end up with 100 as the area. One example is a rectangle of size 1 by 100.
Once you have the area, there is no way to change that to linear feet which is distance. One is two dimensional and one is one dimensional,