I've tried 750 and 500 and they were both wrong. Not sure what the right answer is or what I'm doing wrong

Question 6 2.5 pts Jones Ice Cream Stand is operated by Mr. Jones and experiences different sales patterns throughout the year. To plan for the future, Mr. Jones wants to determine its cost behavior patterns. He has the following information available about the ice cream stand's operating costs and the number of soft serve cones served. Month April May June July August September Number of ice cream cones 800 825 1,125 2,000 1,500 900 Total operating costs $950 $975 $1,000 $1,250 $1,875 $1,500 Using the high-low method, the fixed costs for a month are O $2,200. O $750. O $500. O $300