Required information The following information applies to the questions displayed below.] 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: Units Shipped Month January February March April May June July Total Shipping Expense $ 1,900 $ 2,400 $ 1,800 $ 2,100 $ 2,400 $ 3,400 $ 1,300 in 0 2. Using the high-low method, estimate the cost formula for shipping expense. Variable shipping expense Fixed shipping expense per unit per month