what is the variable shipping expense? its not 250 or 2.50

Required information The following information applies to the questions displayed below.] art 1 of 2 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 eBook Month January February March April Total Shipping Expense $ 1.800 $ 2,300 $1,700 $ 2,000 $ 2,300 $ 2,700 $ 1,200 Print References June July 2. Using the high-low method, estimate the cost formula for shipping expense. $ 28 Variable shipping expense Fixed shipping expense