Can you explain how to solve this math problem: Thomas is making hummus. One of the ingredients in a hummus recipe is chickpeas. For one serving of hummus, the recipe calls for 1 cup of chickpeas. In a can of chickpeas, there are 16 ounces of chickpeas. In one cup of chickpeas, there are 6 ounces. To make 20 servings, how many cans of chickpeas should Thomas buy?