4. Expenses

	2020 $m	2019 $m
Cost of sales¹	8,512	9,440
Administrative expenses	238	289
Employee benefits expenses	635	601
Other expenses
(Gain)/loss on fair value of financial instruments	(328)	198
Contracts and materials	288	306
Impairment loss on trade receivables (net of bad debts recovered)	119	120
Marketing expenses	45	53
Short term lease and outgoings expenses	22	12
Impairment loss on investment in a joint venture	14	-
Acquisition costs	7	-
Net loss on disposal of property, plant and equipment	9	-
Derecognition of assets and costs associated with exit of business	-	47
Net loss on disposal of joint operation	-	2
Other	259	168
Total expenses	9,820	11,236