So first you would set up the equation of 48 = x + x + 3(2)x + 3(2)x. Perimeter is equal to width + width + length + length-- x is width, length is 3 times 2x, so that's where that equation comes from. You combine like terms and get 48 = 2x + 6x + 6x or 48 = 14x. You then divide by 14 and get x ≈ 3.4. Then to find the dimensions you substitute it back to what I said the dimensions were. Width is x, so width is around 3.4. Length is 3 times twice the width (x) so 3(2x) or 6x. So you substitute ≈3.4 for x and get ≈20.6. The width is ≈3.4 and the length is ≈20.6 (the dimensions).
