A mixture of 150 liters of wine and water contains 20% water. How much more water should be added so that water becomes 25% of the new mixture?

Sure, here is the step by step solution:

1. First, we need to find out how much water is currently in the mixture. Since the mixture is 20% water, we multiply 150 liters by 20% (or 0.20) to get 30 liters. So, there are currently 30 liters of water in the mixture.

2. Next, we need to determine how much water would be 25% of the new mixture. Let's denote the amount of water to be added as x liters. The new mixture will then be 150 liters + x liters.

3. We set up the equation: 30 liters (current amount of water) + x liters (amount of water to be added) = 25% of (150 liters + x liters).

4. Solving this equation will give us the amount of water that needs to be added to the mixture.

5. The equation becomes: 30 + x = 0.25 * (150 + x)

6. Simplifying the equation gives: 30 + x = 37.5 + 0.25x

7. Subtract 0.25x from both sides to get: 0.75x = 7.5

8. Finally, divide both sides by 0.75 to solve for x: x = 10

So, 10 liters of water should be added to the mixture to make water 25% of the new mixture.