Answer: 20 liters
Explanation:
The mixture is 60 liters. The ratio is 2 : 1 (2 parts to one part)
60 ÷ (2 + 1) = one part
60 ÷ 3 = 20
Therefore, the ratio of 2 : 1 means 2(20) liters milk to 1(20) liters water
If we change it to a ratio of 1 : 2, then we have 1(20) liters milk to 2(20) liters water.
2:1 ratio has 20 liters water
1:2 ratio has 40 liters water
The amount of water added is 40 - 20 = 20 liters