hello :
x : the width y : The length y>x
xy = 27...(1)
y= x+6...(2)
subst in (1) : x(x+6) = 27
x² +6x -27 =0
Δ = 6²-4(1)(-27) =144= 12²
x1= (-6-12)/2 < 0 refused ( x>0 )
x2= (-6+12)/2 =3
in (2) : y = 3+6 = 9
The length is : 9 feet
the width is : 3 feet