So first to find the perimeter, you need to find the lengths of the sides. Since you have the area, you know that 216=length x width. Use w for width, and 6w for length (since length is 6 times the width). So 216= 6w x w = 6w^2. Divide this by 6 and you get 36=w^2. So now we know that width=6. And we know that length is 36. Now all you have to do is add those together. 36+36+6+6=84. Perimeter = 84 inches. (you can check your work by multiplying 36 x 6 which equals 216: the area you were given).
