One and eighty five. 1x85=85 but 85 isnt prime>>>
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.
_____
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).
Answer:
4
Step-by-step explanation:
You divide the difference of the y-coordinates of 2points on a line by the difference of the x-coordinates of the same 2points
![\left[\begin{array}{ccc}1&3&7\\1&1&1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D1%263%267%5C%5C1%261%261%5Cend%7Barray%7D%5Cright%5D%20)
multiply 2nd row by -1 and add to first row
![\left[\begin{array}{ccc}0&2&6\\1&1&1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D0%262%266%5C%5C1%261%261%5Cend%7Barray%7D%5Cright%5D%20)
divide the 1st row by 2
![\left[\begin{array}{ccc}0&1&3\\1&1&1\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D0%261%263%5C%5C1%261%261%5Cend%7Barray%7D%5Cright%5D%20)
multiply the first row by -1 and add to 2nd row
![\left[\begin{array}{ccc}0&1&3\\1&0&-2\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D0%261%263%5C%5C1%260%26-2%5Cend%7Barray%7D%5Cright%5D%20)
now we know
y+3=0
x-2=0
therefor
y=-3
x=2
