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 $ 2,100 January February March April May June July 4756892 $ 2,600 $ 2,000 $ 2,300 $ 2,600 $ 3,600 $ 1,500 2. Using the high-low method, estimate the cost formula for shipping expense. Variable shipping expense Fixed shipping expense per unit per month