Tap 'A' can fill the tank completely in 6 hrs while tap…

Tap 'A' can fill the tank completely in 6 hrs while tap 'B' can empty it by 12 hrs. By mistake, the person forgot to close the tap 'B', As a result, both the taps, remained open. After 3 hrs, the person realized the mistake and immediately closed the tap 'B'. In how much time now onwards, would the tank be full?

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 #12288