A flower garden is shaped like a circle. Its radius is 16 yd. A ring-shaped path goes around the garden. Its outer edge is a circle with radius 21 yd.
The gardener is going to cover the path with sand. If one bag of sand can cover 7 yd^2, how many bags of sand does the gardener need? Note that sand comes only by the bag, so the number of bags must be a whole number. (Use the value 3.14 for pi.)
