SOLUTION: Mr. Bondi is replacing the square tiles in his bathroom. Each new tile is 3 inches longer and 3 inches wider than an old tile. Each new tile covers 39 square inches more than an

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Question 1075453: Mr. Bondi is replacing the square tiles in his bathroom. Each new tile is 3 inches longer and 3 inches wider than an old tile. Each new tile covers 39 square inches more than an old tile.
A) How big were the old tiles? ____ inches by ____ inches
B) If the area of a room is 5120 square inches, how many new tiles will he need? _____ tiles.

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
let l be the length of the old tile and w be the width of the old tile, then
:
The area of the new tile minus the area of the old tile equals 39
:
(l+3)(w+3) -lw = 39
:
lw +3l +3w +9 -lw = 39
:
3l +3w = 30
:
l +w = 10
:
We know that the area of the old tile is maximized when l = 5 and w = 5
:
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A) 5 inches by 5 inches
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:
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B) The area of a new tile is (5+3)(5+3) = 64 square inches
Note that 25 + 39 = 64
5120 / 64 = 80 new tiles
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