Q2: The last selection is appropriate.
For a square lawn of area 8x, the length of one side is √(8x). If 2 feet are added to each end, the total length is
.. 2 +√(8x) +2 = √(8x) +4
If this length exceeds the 20 feet of pavers that Aroldo purchased, then there will NOT be enough to complete the project. Hence the inequality you want is
.. √(8x) +4 > 20