Speedy Delivery Services has the collected the following information about operating expenditures for its delivery truck fleet for the past five years(3 points): Year Miles Operating Costs 2007 110,000 $390,000 2008 140,000 $420,000 2009 100,000 $360,000 2010 130,000 $410,000 2011 150,000 $440,000 a. Using the high-low method, what is the cost estimate for variable costs for 2012? b. Using the high-low method, what is the cost estimate for fixed costs for 2012? c. What is the best estimate of total operating expenses for 2012 using the high-low method based on total expected miles of 120,000