A dealer offers a cash discount of 10% and still makes a…

A dealer offers a cash discount of 10% and still makes a profit of 20% when he further allows 45 articles to be sold at the cost price of 40 articles to a particular sticky bargainer. How much percent above the cost price were his articles listed?

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 #37937