Using the high-low method, what is the fixed cost per month?

Tool Content January February March April May June July August Number of Copies 40,000 35,000 60,000 80,000 85,000 75,000 82,000 105,000 Total Copy Cost $3,500 $3,200 $ 4,100 $ 5,100 $ 5,600 $ 4,800 $5,300 $ 6,000