A family made a down payment of …500

A family made a down payment of $75 and borrowed the balance on a set of encyclopedias that cost $500. The balance with interest was paid in 23 monthly payments of $20 each and a final payment of $9. The amount of interest paid was what percent of the amount borrowed?

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 #1589