Carrefour Group (headquartered in Boulogne‑Billancourt, France) and Tesco PLC (headquartered in Welwyn Garden City, UK) compete head‑to‑head in the grocery space in the UK, Ireland, Central Europe, and North Africa. 

The following information comes from their 2018 annual reports.

	Carrefour Group in		Tesco PLC in
	€ millions		£ millions
	2018	2017	2018	2017
Sales	€ 73,720	€ 75,966	£55,766	£54,239
Cost of sales	60,850	62,311	54,141	53,015
Gross profit	12,870	13,655	1,625	1,224
Inventory	5,951	6,489	2,195	2,232
Total assets	47,378	47,813	44,862	45,853

Required

a. Calculate gross profit margin for each year for both companies.

b. Compute inventory turnover and days average inventory outstanding for 2018.