26 buses are running between two places P and Q

26 buses are running between two places P and Q. In how many ways can a person go from P to Q and return by a different bus?

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 #9132