Find the total area of the wall, including the window area: (10 ft)(12 ft) = 120 ft^2.
Next, find the window area: (3 ft)^2 = 9 ft^2
and, finally, subtract the window area from the total wall area: (120-9) ft^2, or
111 ft^2. The total amount of wallpaper needed, with zero waste, is 111 ft^2.