<span>we are given with a swimming pool with dimensions </span>12-ft-by-15-ft. given that there is a <span>3-ft-wide no-slip surface around it, the new dimensions now become (12+3+3) or 18 ft by (15+3+3) or equal to 21 ft. The perimeter is the sum of the sides of the new rectangle. Perimeter is equal to 18+ 18 + 21 + 21 or equal to 78 feet</span>