Answer:
5
Step-by-step explanation:
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).
For this case we have that by definition, the equation of a line in the slope-intercept form is given by:

Where:
m: Is the slope
b: Is the cut-off point with the y axis
We have the following equation:

We manipulate algebraically:
We subtract 10 from both sides of the equation:

We subtract 3x from both sides of the equation:

We multiply by -1 on both sides of the equation:

We divide between 5 on both sides of the equation:

Thus, the equation in the slope-intercept form is 
Answer:

The anwser is for the question tht u are looking for is no other then the first anwser A!!!