Supply chain model for the retailer's ordering policy under two levels of delay payments derived algebraically

The main purpose of this note is to investigate Huang's model and extend Huang's model by considering the selling price per item higher than the purchasing cost per item to determine the optimal ordering policy for the retailer under two levels of delay payments. Then, an algebraic approach is provided and an easy-to-use procedure developed to find the optimal ordering policy for the retailer. Finally, a numerical example is given to illustrate the theoretical results.