For a rectangle
Area = Length x Width
A = L x W
A = 27 ft2
L = W + 6
A = W(W + 6)
27 = W2 + 6W
A quadratic can be applied here, subtract 27 from both sides
0 = W2 + 6W - 27
Factoring
(W + 9)(W - 3) = 0
W cannot be negative 9 so W = 3
Substituting, according to information given
L = 3 + 6 = 9
Length = 9 ft
Width = 3 ft
I hope you find this useful, if you have any questions please send me a message.