ALGEBRA HELP!!!!!!!! 10 POINTS!?

The Lush Landscaping Company is involved in a project for the city. The garden is front of city hall is going to be expanded by a planting border of flowers all the way around it. The current dimensions of the garden are 24 ft long by 16 ft wide. The border will have the same width around the entire garden. The flowers that will be planted in the border will fill the area of 276 ft^2. Find the width of the border surrounding the garden by using symbolic representation