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?

Number of liters of water in 125 liters of the mixture = 20% of 150
= 1/5 of 150
= 30 liters

Let us Assume that another 'P' litres of water is added to the mixture to make water 25% of the new mixture.
So, the total amount of water becomes (30 + P) and the total volume of the mixture becomes (150 + P).

Thus, (30 + P) = 25% of (150 + P)
⇒ 30 + P = 25/100 of (150 + P)
⇒ 30 + P = (1/4) × (150 + P)
⇒ 120 + 4P = 150 + P
⇒ 4P - P = 150 - 120
⇒ 3P = 30
⇒ P = 10

10 Litres of water is added to the mixture to make water 25% of the new mixture.