2) Let x=width ; x+8=length
Area = x(x+8) = x² +8x
3) Area of cemented portion = Area of pathway - area of manhole
= x² +8x - 0.5
4) 19.5 = x² +8x - 0.5
5) Solve for the values of x using (4):
19.5 = x² +8x - 0.5
0 = x² +8x - 0.5 -19.5
0 = x² +8x -20
0 = (x-2) (x+10)
x=2 ; x=-10 [use x=2 because there is no negative dimension]
Width = 2 m
Length = 10 m [from x+8]