###Human: Arthur has 3 dogs. They eat an average of 15 pounds of food a week. One dog eats 13 pounds a week. The second eats double this. How much does the third dog eat a week?, ### Assistant: The second dog eats 26 pounds a week because 13 x 2 = 26
In total they eat 45 pounds because 3 x 15 = 45
The third dog eats 6 pounds a week because 45 - 13 - 26 = 6 
 So the answer is :  6