9514 1404 393
Answer:
65 feet
Explanation:
The problem involves finding the perimeter of a rectangle, then making adjustments to remove parts of the perimeter that aren't wanted.
The perimeter of a rectangle is given by the formula ...
P = 2(L+W)
For Aubrey's 12' × 8' room, the perimeter is ...
P = 2(12' +8') = 40'
This is the length of the border Aubrey needs at the ceiling.
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At "waist-high", we need to subtract the total width of all the windows and doors. That total is ...
3' + 4' + 3' + 5' = 15'
So, the waist-high border is 40' -15' = 25'.
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The total amount of border Aubrey needs is ...
ceiling border + waist-high border = 40' + 25' = 65'.
Aubrey needs 65 feet of border.