I would love to understand how to solve this problem: Josh built his little brother a rectangular sandbox.  The perimeter of the sandbox is 30 feet and the length is twice the width. What is the width of the sandbox?
Can you explain?
There are four sides to a rectangle, the width is W and so the length is 2W, and we can put that in this equation: W + W + 2W + 2W = 30 feet.
If we add the sides together, we get 6W = 30 feet.
To find W, we divide both sides by 6, like this: 6W / 6 = 30 feet / 6, so W = 5 feet.