Respuesta :
The problem is literally telling you the answer. The perimeter would be 324. It is just giving you extra information in the problem that is probably making you confused.
In order to find the perimeter, you have to find the length. It says the area is 324 suare feet, so you must divide 324 by 12 to find length. Once you have length, you have a rectangle. Perimeter is 2 times the length plus 2 times the width, so subsequently the answer is 78 feet.