Final answer:
Tank ate 2 6/7 pounds of dog food each day, calculated by dividing the 20-pound bag of food by 7 days.
Step-by-step explanation:
To determine how much dog food Tank ate each day, divide the total amount of dog food by the number of days it lasted. Ruben bought a 20-pound bag of dog food, and it lasted for 7 days.
So, the calculation is:
20 pounds รท 7 days = 2 6/7 pounds per day.
You can leave the answer as an improper fraction, which is 2 6/7, or you can convert it to a mixed number, which remains the same since it is already in that form, or to a decimal, which is approximately 2.857 pounds per day.