Two trains are running in opposite directions with the same speed

Two trains are running in opposite directions with the same speed. If the length of each train is 300 metres and they cross each other in 12 seconds, then the speed of each train (in km/hr) is:

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 #25037