Safety Window and Door Co. buys on terms of 2/15, net 60 days. It does not take discounts, and it typically pays on time, 60 days after the invoice date. Net purchases amount to $450,000 per year. On average, how much "free" trade credit does the firm receive during the year? (Assume a 365-day year, and note that purchases are net of discounts.)

a. $18,493

b. $20,389

c. $22,479

d. $21,408

e. $19,418