High-Low Method The manufacturing costs of Kellam Industries for the first three months of the year follow: Using the high-low method, determine (a) the variable cost per unit and (b) the total fixed cost. a. Variable cost per unit X b. Total fixed cost X Feedback Check My Work a. Divide the difference between the highest and lowest total costs by the difference between the highest and lowest production units. b. Multiply the variable unit cost by the number of units for a month. Subtract this variable cost from the month's total cost to arrive at the total fixed cost. The resulting amount should be the same for either the highest or lowest production month