If this was solved on your own and not via GPT Chat, you are a genius.

There's a mistake here. I had to write it that way, otherwise it wouldn't accept the answer. You need to correct the comparison character in the next line:
if (rent_day >= 7) return total_amount = (rent_day * rent_day_price) - 20;

You are correct, I changed the comparison symbol and the problem became correct. The error is in the problem itself.