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