Acarpenter is framing a window with wood trim where the length of the window is 9 1/3 feet. if the width of the window is 6 3/4 feet, how many feet of the wood is needed to frame the window?

This is not much of a question, because it doesn't take into account the width of the wood trim.  

So you are asked to find the perimeter of the window, ignoring the width of the trim.

P = Perimeter = 2L + 2W.

Here, P= 2(9 1/3 feet) + 2(6 3/4 feet) = 2(28/3 feet) + 2(27/4 feet)

So P = 2[28/3 + 27/4] feet.  LCD is 3*4 = 12.

Thus, P = 2 [ 28/3 + 27/4 ] feet.  Can you finish?  Add together the fractions 28/3 and 27/4.