By selling a book for 300, 20% profit was earned

By selling a book for 300, 20% profit was earned. What is the cost price of the book?

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 #37879