We are given the following information
Length of rectangular deck = 12 feet
Perimeter of rectangular deck = 36 feet
Recall that the perimeter of rectangular shape is given by
Where l is the length, w is the width, and P is the perimeter of the rectangle.
Let us substitute the given values and solve for width (w)
Therefore, the deck's width is 6 feet
Recall that the area of a rectangular shape is given by
Where l is the length and w is the width of the rectangle.
Therefore, the deck's area is 72 square feet.