## Precalculus (6th Edition)

(34-2x) (21-2x) $=$ 600
The picture is surrounded by a frame from all sides, whose dimensions are, 34in $\times$ 21in. To find the dimensions of the picture, we need to subtract the border. Length of picture $=$ $34-x-x$ $=$ $34-2x$ Width of picture $=$ $21-x-x$ $=$ $21-2x$ Now we have the dimensions of the picture. To find the area (which in this case is given as 600 $in^{2}$), we need to multiply the length and breadth. ie, (34-2x) (21-2x) $=$ 600 Thus the answer is option B.