I sold a book at a profit of 10%

I sold a book at a profit of 10%. Had I sold it for $120 more, 15% would have been gained. Find the cost price?

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 #45240