Jackie needs to buy chicken feed for her chickens. She can buy a 40-pound bag for $30.99 or a 10-pound bag for $12.98. Which size bag is cheaper per pound? Round to the nearest penny, if necessary
To find the price per pound for the 40-pound bag, divide the cost by the number of pounds: $30.99 / 40 pounds = $0.77475... per pound, which rounds to $0.77 per pound.
To find the price per pound for the 10-pound bag, divide the cost by the number of pounds: $12.98 / 10 pounds = $1.298 per pound, which rounds to $1.30 per pound.
Since $0.77 per pound is less than $1.30 per pound, the 40-pound bag is cheaper per pound. Answer: \boxed{40}.