Toby owns a bar and is reviewing their costs for the month of June. The following is Toby's list of expenses. They had 600 patrons visit their bar this month, with a majority of their revenue coming in on Friday and Saturday nights; however, sometimes this was not true, and they had to call in employees to work or send some home based on how busy they were. What is the equation of a line for the total cost function?

Rent	$1800
Utilities	$600
Wages	$2,500
Glassware	$200