Question 978755
Maybe to mean, 
Square painting of area 9 ft^2 is mounted on or in a square frame, and the area of the frame border around the picture is 3.25 ft^2.  Find the length of any side of the frame.


The uniform width of the border around the picture is a number, x.
If 9 sq.ft.  is area of the picture, then 3 feet is the side of this square picture.


Area inside the frame, {{{(3+2x)(3+2x)}}}
Area of just the picture, {{{3*3=9}}}, already given.
Area of the border around the picture, of just the frame itself,  {{{highlight((3+2x)^2-3*3=3.25)}}}.


Solve for x using a few steps of algebra & arithmetic.  Note that the question really means, find the value for {{{3+2x}}}.


----further thought,
Solving for x is not necessary.  You CAN just solve the equation for 3+2x.
-
{{{(3+2x)^2=3.25+9}}}
{{{3+2x=sqrt(12.25)}}}
{{{highlight(3+2x=3.5)}}}.