Consider the question. Hannah is making banana bread. She needs to use 3 cups of flour for every cup of banana mush. It takes 4 bananas to make one cup of mush. If Hannah uses 20 bananas, how many cups of flour should she use?
 What is the step-by-step reasoning process to arrive at the answer: 15?
First find the number of cups of banana mush Hannah gets: 20 bananas / 4 bananas / cup = 5 cups. Then multiply the number of cups of mush by the ratio of flour to mush to find the number of cups of flour: 5 cups mush * 3 cups flour / 1 cup mush = 15 cups flour.