In a mixture, the ratio of milk to water is 5:1. When 20 liters of water is…

Define the initial quantities:

The initial ratio of milk to water is 5:1.

Let the quantity of milk be 5x liters and the quantity of water be 1x liters.

Account for the addition of water:

20 liters of water are added to the mixture.

The new quantity of water becomes (x + 20) liters.

Set up the equation based on the new ratio:

After adding water, the ratio of milk to water becomes equal, which means the ratio is 1:1.

Therefore, the quantity of milk equals the new quantity of water:
5x = x + 20

Solve for x:

Subtract x from both sides:
4x = 20

Divide by 4:
x = 5

Calculate the quantity of milk:

The quantity of milk is 5x.

Substituting x = 5:
5 * 5 = 25 liters.

The quantity of milk in the final mixture is 25 liters, which corresponds to Option 1.