A payment of $500 within the discount period reduced the balance owed on an invoice from $1450.61

Question:

A payment of $500 within the discount period reduced the balance owed on an invoice from $1450.61 to $943.00. What was the for prompt payment?
Discount Rate
Depending upon the context, the discount rate has two different definitions and usages. First, the discount rate refers to the interest rate charged to the commercial banks and other financial institutions for the loans they take from the Federal...