Consider the question. On a farm, on average every 6 cows produce 108 liters of milk per week. In five weeks the cows produced 2160 liters of milk. How many cows are on the farm?
 What is the step-by-step reasoning process to arrive at the answer: 24?
Per week, one cow produces 108 liters / 6 cows = 18 liters / cow. The cows produced 2160 liters of milk over 5 weeks. So we have 2160 liters / 18 liters / cow = 120 cows. Further, we have to divide 120 cows / 5 weeks = 24 cows.