Can you help me understand how to work this?

Dome Metals has credit sales of $216,000 yearly with credit terms of net 45 days, which is also the average collection period. Assume the firm adopts new credit terms of 2/15, net 45 and all customers pay on the last day of the discount period. Any reduction in accounts receivable will be used to reduce the firm's bank loan which costs 9 percent. The new credit terms will increase sales by 10% because the 2% discount will make the firm's price competitive. a. If Dome earns 20 percent on sales before discounts, what will be the net change in income if the new credit terms are adopted? (Use a 360-day year.)