A = W· L
10,000 = W ( W +30 ) = W² + 30 W
W² + 30 W - 10,000 = 0
W =

L = 86.12 + 30 = 116.12
Width of a plot is 86.12 m and lenght is 116.12 m.
Check : A = 116.12 · 86.12 ≈ 10,000
The table shows a linear function :)
33+9= 42+12= 54+2=90-56= 34 34+3x
I don't know
2+2=2x+2
-2 to both sides
2=2x
Divide 2
X=1