I don't know how to explain but the answer is 2.4.
There are no real solutions to solve Z. If there may be a typo or something, there are no solutions.
Answer:
-5 and -4
Step-by-step explanation:
It is far easier just to solve the equation than to determine appropriate integer bounds on the solution.
In the attachment, we show a couple of initial trials at solutions. The nearness of y=5 to being correct suggests that the next higher integer may be helpful, too. It is.
We find -4 and -5 to bracket the solution.
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The actual solution is (3.4 -1.3)/-0.5 = -4.2.
The wall area is the product of the room perimeter and the room height:
A₁ = (2*(12.5 ft + 10.5 ft))*(8.0 ft) = 368 ft²
The window and door area together is
A₂ = 2*((4 ft)*(3 ft)) + (7 ft)*(3 ft) = 45 ft²
The area of one roll of wallpaper is
A₃ = (2.5 ft)*(30 ft) = 75 ft²
Then the number of rolls of wallpaper required will be
1.1*(A₁ - A₂)/A₃ ≈ 4.74
5 rolls of wallpaper should be purchased.
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As a practical matter, not much of the window and door area can be saved. The rolls are 30 inches wide, but the openings are 36 inches wide. Some will likely have to be cut from two strips. The strips will have to be the full length of the wall, and the amount cut likely cannot be used elsewhere. If the window and door area cannot be salvaged, then likely ceiling(5.4) = 6 rolls will be needed (still allowing 10% for matching and waste).
