A 150-liter mixture of wine and water contains 20% water. How many additional liters of water must be added so that water makes up 25% of the resulting mixture?

Explanation

Initially, the mixture contains 20% water, which is 0.20 × 150 = 30 liters of water. Let the amount of water added be P liters. After adding water, the total water volume is (30 + P) liters, and the total mixture volume is (150 + P) liters. To have water at 25% of the new mixture, set up the equation: (30 + P) = 0.25 × (150 + P). Solving, 30 + P = 37.5 + 0.25P leads to 0.75P = 7.5, so P = 10 liters.