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A border of uniform width is placed around a rectangular photograph that measures 8 inches by 10 inches. If the area of the border is 144 square inches, what is the width of the border, in inches?
Area of photo = 8*10 = 80 sq. in.
Area of border = 144 sq. in (given)
New area of photo along with the border = 80+144 = 224 sq. in.
Now we can find new lengths in equal integer increments of 8 and 10 (since answer choices are integers)
+6 works as (8+6)*(10+6) = 16*14 =224
Last step, since border is of equal width on either side of the length and width of the photo, then the width of the border is 6/2 = 3.
