Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
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?

### Response:
Hannah will get 20 / 4 = <<20/4=5>>5 cups of banana mush.
Hannah should use 3 * 5 = <<3*5=15>>15 cups of flour.
#### 15