Miguel wants to wallpaper the back wall of his bedroom. the wall is in the shape of a rectangle. its length is 13 feet and its width is 12 feet. supposed wallpaper costs $8 for each square foot. how much will wallpaper cost for the wall

First of all lets find the area of the rectangle.
13 ft × 12 ft = 156 square feet.
Now lets find the price which is $8 / square foot. Using proportions we get:
$8/sq ft × 156 sq ft. Simplifying we get
$8 × 156 = $1248.
The wallpaper will cost $1248