Global Publishers has collected the following data for recent months: Month Issues published Total cost March 20,500 $20,960 April 21,800 22,464 May 17,750 18,495 June 21,200 21,395 Required: a. Using the high-low method, find variable cost per unit, total fixed costs, and the total cost equation. b. What is the estimated cost for a month in which 19,000 issues are published