i thoight for the last one i would do 5440 - (750x7) but its not working. what am i doing wrong

The controller of Sandhill Industries has collected the following monthly expense data for use in analyzing the cost behavior of maintenance costs. Total Machine Hours Month Total Maintenance Costs $2,640 2,940 January 350 February March 3,540 4,440 April May 3,140 5440 June Your answer is correct. Determine the variable cost components using the high-low method. (Round answer to 2 decimal places e.. 2.25.) Variable cost per machine hour $ e Textbook and Media * Your answer is incorrect, Determine the fixed cost components using the high-low method Total foed costs $ 32830