A big container is 50% full with water

A big container is 50% full with water. If 20 liters of water is added, the container becomes 3/4 full. What is the capacity of the big container in liters?

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 #70817