Without stoppages a train travels a certain distance with an average speed…

Without stoppages a train travels a certain distance with an average speed of 80 kmph and with stoppages it covers the same distance with an average speed of 40 kmph. What is the time in minutes per hour for which train stops?

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 #22820