Answer: 3 hours
Explanation: There are 24 hours in a day, and the robots use 2 bags of coffee a day, so you gotta do 24/2 and that means 1 bag of coffee lasts 12 hours. Next, the question is how long does 1/4 bag last, so you do 12/4 and get 3, therefore the correct answer is 3 hours. Hope this helped!