### Instruction: What quantity of water should taken out to concentrate 21 liters of 40% acidic liquid to 60% acidic liquid?
Answer Choices: (A) 5liters (B) 10liters (C) 7liters (D) 8liters (E) 6liters.### Response: Let's think about the multi-choice question.
Required answer is = 21(60-40)/60 = 7 liters
The answer is C