Calculate how much time could be saved if the train would run…

Calculate how much time could be saved if the train would run at its usual speed, given that it ran at 4/9 of its own speed and got to its destination in 13 hours?

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 #45867