The following data have been extracted from the records of Puzzle, Inc.: February August Production level, in units 9000, 20700 variable costs $ 26100 $ ? Fixed costs ? 30900 Mixed costs 25710 ? Total costs $ 82710 $ 143433 Required: a. Calculate the missing costs. (Do not round intermediate calculations.) b. Calculate the cost formula for mixed cost using the high-low method. (Do not round intermediate calculations. Round "Variable cost" to 2 decimal places.) c. Calculate the total cost that would be incurred for the production of 14,060 units. (Do not round intermediate calculations.) d. Identify the two key cost behavior assumptions made in the calculation of your answer to part c.