The volume V of a cube is given by
where L is the lenght of one side. Hence, the side L measures
In the first case, the dog kennel has 27 ft^3 of volume, hence
that is, L is 3 feets of lenght.
In the same way, for the second case we have that,
that is, in the second case, L is 4 feet of lenght. This means that, 1 foot was added to each edge of the dog kennel.