the height of the wall is 10 ft
the area of each section is 10
NOw divide the height of the wall in equal 5 parts.
10/5 = 2 ft ( height of each section)
as an area of the section is 10
2 x l = 10
l = 10/2
l = 5 ft
so the length of each section is 5 ft
so total length of the wall is 5 x 5 = 25 square ft.