Question 816
Let width of the border be x.
Therefore width of the carpet will be 13-2x (you have to subtract both sides)
Similarly length will be 16-2x.

Therefore area of the carpet = (16-2x)(13-2x) = 108
208 - 58x + 4x^2 = 108
4x^2 - 58x +100 = 0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
Where a=4, b=-58, c=100
x=-2 or 12.5
But you know width of the border cannot be 12.5 because the width of the floor is only 13.
Therefore width of the border is 2 ft.

Hope you will understand