I'm stuck on this one.... I can't figure out the echelon portion of this and what formulas to use.

Suppose a new, centralized warehouse is added to serve Atlanta, Boston, Chicago, and Dallas as shown in Figure 1c. The manufacturing facility will continue to serve the Los Angles warehouse given its proximity and newly added centralized warehouse. Assuming that all warehouses are following the continuous review inventory policy, compute and describe its inventory management policy and associated cost. Keep in mind that the centralized warehouse is one echelon above regional warehouses. Ignore inbound and outbound transportation cost. Provide answers and calculations for order quantity, demand during lead time, safety stock, average inventory level, inventory holding cost per week, ordering cost per week, and total cost per week.

	Q*	Ddlt	SS	Avg Inv	Inv cost	Ord Cost	Tot Cost
Atlanta
Boston
Chicago
Dallas
LA
Central Warehouse
	Total cost of the distribution system 1c
	Total cost of the distribution system 1a
	Total cost of the distribution system 1b

Information:

90% servie rate / z=1.29

		order cost	holding cost/unit
mixed model	central warehouse	$ 3,000.00	$ 1.00
	fegional wareshoue	$ 3,000.00	$ 1.25

HISTORICAL demand for 12 weeks
Week	1	2	3	4	5	6	7	8	9	10	11	12
Atlanta	33	45	37	38	55	30	18	58	47	37	23	55
Boston	26	35	41	40	46	48	55	18	62	44	30	45
Chicago	44	34	22	55	48	72	62	28	27	95	35	45
Dallas	27	42	35	40	51	64	70	65	55	43	38	47
Los Angels	32	43	54	40	46	74	40	35	45	38	48	56