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

### Instruction:
Compared to the amount of water she drank, Carla drank three times as much soda minus 6 ounces. If she drank 54 ounces of liquid total, how much water did she drink?

### Response:
Let s be the amount of soda Carla drank and w the amount of water she drank. We know that s + w = 54 and s = 3w - 6. Substituting the second equation into the first equation, we get 3w - 6 + w = 54.
Combining like terms, we get 4w - 6 = 54.
Adding 5 to both sides, we get 4w = 60.
Dividing both sides by 4, we get w = 15.
#### 15