Milk contains 10% water

Milk contains 10% water. What content of pure milk should be added to 20 liters of milk to reduce this to 5%?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #11493