The following data relating to units shipped and total shipping expense have been assembled by Archer Company, a wholesaler of large, custom-built air-conditioning units for commercial buildings Month Units produced Total shipping expense ($) January 3 $ 1,800 February 6 $ 2,300 March 4 $ 1,700 April 5 $ 2,000 May 7 $ 2,300 June 8 $ 2,700 July 2 $ 1,200 A. Using the high-low method, estimate a cost formula for expense. (10 marks) B. Describe the advantages and disadvantages of finding the fixed and variable elements of semi- variable costs using scattergraph