Algebra-2

Question Analysis
This problem assesses the ability to solve rational equations in a real-world context involving mixtures and concentrations.

Key Concept Explanation
To find the amount of pure water to be added, we need to set up an equation based on the initial and final concentrations of the acid in the mixture.

Step-by-step Solution
1. Let be the amount of pure water to be added.
2. The initial amount of acid is liters.
3. The final volume of the mixture is liters.
4. The final concentration is 15%, so the amount of acid in the final mixture is liters.
5. Set up the equation: