Final answer:
The equation that can find the length and width of the sandbox is P = 2L + 2W (option D). By substituting the given values into the equation and solving, we can determine the dimensions of the sandbox.
Step-by-step explanation:
The equation that can find the length and width of the sandbox is P = 2L + 2W (option D).
Since the length (l) of the sandbox is one foot longer than the width (w), we can express the length as w+1. The perimeter (P) of a rectangle is given by the formula P = 2L + 2W. Substituting w+1 for L and w for W, we get P = 2(w+1) + 2w.
Simplifying the equation, we get P = 4w + 2. Since we know that the perimeter is 18 feet, we can substitute 18 for P and solve for w. 18 = 4w + 2. Rearranging the equation, we get 4w = 16. Dividing both sides by 4, we get w = 4.
Therefore, the width of the sandbox is 4 feet, and the length is one foot longer, which is 5 feet.