20. Casey bought a 100-pound bag of dog food. He gave his dogs the same amount of dog food each week. The dog food lasted 8 weeks. How much dog food did Casey give his dogs each week? Give the answer as a fraction or mixed number.

Casey had a total of 100 pounds of dog food that lasted for 8 weeks. To find out how much dog food he gave his dogs each week, you divide the total amount by the number of weeks: \( \frac{100 \text{ pounds}}{8 \text{ weeks}} = 12.5 \text{ pounds} \). As a mixed number, that's \( 12 \frac{1}{2} \) pounds of dog food each week! So, Casey fed his dogs \( 12 \frac{1}{2} \) pounds of dog food weekly, ensuring they were well-fed while being cost-effective with his 100-pound bag!