On December $10$ your business sold inventory worth $$25,000$ to a customer for $$45,000.$ You shipped it FOB destination and the terms were $\frac{1}{10},\frac{n}{30}.$ The next day, the appropriate party paid the freight company $$100.$ Four days later the customer returned $20\%$ of his order. You received payment on December $22.$ How much did the customer pay you? $(2$ points$)$