Bunuel wrote:

The front of a 6-foot-by-8-foot rectangular door has brass rectangular trim, as indicated by the shading in the figure above. If the trim is uniformly 1 foot wide, what fraction of the door's front surface is covered by the trim?(A) 13/48

(B) 5/12

(C) 1/2

(D) 7/12

(E) 5/8

First let's find the area of unshaded region.

The two unshaded regions have a width of 4 feet: 6 feet minus 1 foot wide trim on each side.

The two unshaded regions have a height of 5 feet: 8 feet minus 1 foot at the top, 1 foot in the middle and 1 foot at the bottom.

Thus the area of the two unshaded regions is 4*5=20 square feet.

Therefore, the area of the trim is 6*8-20=28 square feet, which is 28/48=7/12 of the total area.

Answer: D.

Hope it's clear.

Thank you for this. I accidently chose the trap answer of

\frac{5}{12}, and found the area of the door not covered by trim

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