The Aust Corporation has gathered the following data on its copy machine costs for the first eight months of the year. Month Number of Copies Total Copy Cost January 40,000 $ 3,500 February 35,000 $ 3,200 March 60,000 $ 4,100 April 80,000 $ 5,100 May 85,000 $ 5,600 June 75,000 $ 4,800 July 82,000 $ 5,300 August 105,000 $ 6,000

Using the high-low method, what is the variable cost per copy? (Round answer to 2 decimal places, e.g. 15.25.)