Fencing encloses a rectangular backyard that measures 200 feet by 600 feet. A blueprint of the backyard is drawn on the coordinate plane so that the rectangle has vertices (0, 0) , (0, 30) , (10, 30), and (10, 0). A circular flower garden is dug to be exactly in the center of the backyard, with a radius of 40 feet. This garden is represented on the blueprint. What is the equation of the flower garden represented on the blueprint