For each company, calculate the missing amount. (Omit the "$" sign in your response.)

Company	Sales	Cost of Goods Sold	Gross Profit	Operating Expenses	Net Income
Lennon	$8,800	$?	$4,500	$2,400	$2,100
Harrison	8,300	3,100	?	1,100	4,100
McCartney	8,400	3,400	5,000	?	1,500
Starr	7,000	1,900	5,100	2,600	?