Winnie is buying dog food for her dog. She needs 10 pounds of food each week, but has room to store any extra food that she purchases.The food comes in 4 different sizes as given below:
4.2 pounds for $4.99
8.5 pounds for $9.27
12 pounds for $11.04
20 pounds for $18.99
Winnie is trying to be a smart shopper and get the best deal on the dog food. Which size bag of dog food should Winnie buy?