Mrs. Nally's swimming pool is 10 feet by 6 feet. She paves the area around it with a sidewalk x feet wide, using 80 square feet of a new type of non-slip concrete. How wide is the sidewalk? A. The sidewalk is 20 feet wide. B. The sidewalk is 4 feet wide. C. The sidewalk is 10 feet wide. D. The sidewalk is 2 feet wide.