KöMaL 2015 K469

A certain paint needs to be diluted in a $2 : 1.5$ ratio, that is, 2 litres of water need to be added to 1.5 litres of paint. Violette Palette, the artist first made 9 litres of a mixture, half paint, half water. Then she realized that this was the wrong ratio, and calculated how much more water to add to achieve the correct proportion. However, instead of the amount of water needed, she added an equal amount of paint by mistake. The second time she did not make any mistake, and added the appropriate quantity of water required for the correct ratio. How many litres of mixture did she get eventually?