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Archer Company is a wholesaler of custom-built air-conditioning units for commercial buildings. It gathered the following monthly data relating to units shipped and total shipping expense:

Month	Units Shipped	Total Shipping Expense
January	3	$	1,900
February	6	$	2,400
March	4	$	1,800
April	5	$	2,100
May	7	$	2,400
June	8	$	3,400
July	2	$	1,300

2. Using the high-low method, estimate the cost formula for shipping expense.

variable shipping expense per unit?

Fixed shipping expense per month?