[DARISC]

You have before you two containers, the first containing one liter of black colored liquid, the other containing one liter of clear water.

You also have but one other container, an empty one quarter liter cup.

You dip the cup into the black liquid and transfer precisely one quarter liter of the black liquid into the liter of clear water and stir the mixture. Or you don't stir the mixture (for all intents and purposes here, it makes absolutely no difference whatsoever).

You then decide that you wish to balance the quantity of each container so that they each contain one liter of liquid, and that you wish to have each container contain the same percentage of liquid from the other container.

You must do this in one action, using only one or more of the three containers you have on hand

What do you do?

This is not a "trick" problem. It is purely logical.