At the end of the month, a certain ocean desalination plant’s reservoir…

At the end of the month, a certain ocean desalination plant’s reservoir contained 6 million gallons of water. This amount is twice the normal level. If this amount represents 60% of the reservoir’s total capacity, how many million gallons short of total capacity is the normal level?

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 #52670