Final answer:
The correct equation to find the dimensions of the sandbox, where the length is one foot longer than the width, is (2x + 2(x + 1) = 18), representing the perimeter of a rectangle. The width is represented by x, and the length by x + 1.
Step-by-step explanation:
To find the length and width of a child's rectangular sandbox with a perimeter of 18 feet, where the length is one foot longer than the width, you would use the following equation:
(2x + 2(x + 1) = 18)
Here's why: let's define the width of the sandbox as 'x'. Since we know the length is one foot longer, the length would be 'x + 1'. A rectangle's perimeter is calculated by the formula P = 2l + 2w where l is length and w is width. Plugging our expressions for length and width into the perimeter formula, we get:
2x (for the width) plus 2 times (x + 1) (for the length). Simplified, this gives us the correct equation a).