Solution :
For the bigger rectangle
Width of bigger rectangle = W
Length of bigger rectangle, L = 2W
For the smaller rectangle
Width , w = W+4
Length, l = L = 2W
Area, a =120 [tex]m^2[/tex]
Now we know,
Area = length x width
[tex]$a=l \times w$[/tex]
[tex]$120=(2W) \times (W+4)$[/tex]
[tex]$120=2W^2 + 8W$[/tex]
[tex]$2W^2+8W-120=0$[/tex]
[tex]$W^2+4W-60=0$[/tex]
[tex]$(W+10)(W-6) = 0$[/tex]
We get, either [tex]W=-10[/tex] (rejecting)
or [tex]W=6[/tex]
∴ length of the bigger rectangle, [tex]$L=2W $[/tex]
= 2(6)
= 12 m
Length of the smaller rectangle, [tex]$L=2W$[/tex]
= 2(6)
= 12 m
Hence, the length of the two gardens is 12 m.